Method and Apparatus for Performing Spinal Surgery

ABSTRACT

Implants, instruments, and methods for performing surgical procedures on the spine, including one or more of creating an operative corridor to the spine, delivering implants to the spine, fusing one or more segments of the spine, and fixing one or more segments of the spine.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.14/029,724, filed Sep. 17, 2013 (pending); which is a continuation ofSer. No. 13/204,583, filed Aug. 5, 2011 (now U.S. Pat. No. 8,535,320),which is a continuation of U.S. patent application Ser. No. 12/927,415,filed on Nov. 10, 2010 (now U.S. Pat. No. 8,357,184), which claims thebenefit of priority from U.S. Provisional Patent Application Ser. No.61/259,825, filed Nov. 10, 2009 (expired). The contents of all of theforegoing are each incorporated herein by reference.

FIELD

This application relates to implants, instruments, and methods forperforming surgical procedures on the spine, including one or more ofcreating an operative corridor to the spine, delivering implants to thespine, fusing one or more segments of the spine, and fixing one or moresegments of the spine.

BACKGROUND

Spinal discs serve to cushion and stabilize the spine in addition todistributing stress and damping cyclic loads. The discs may becomedamaged due to injury or age and symptoms of a damaged disc may includesevere pain, numbness or muscle weakness. Fusion is one method ofreducing the magnitude of the symptoms of damaged spinal discs, or forany pathology that would suggest direct spinal decompression as atreatment. The primary goals of fusion procedures are to providestability between the vertebrae on either side of the damaged disc andto promote natural fusion of those adjacent vertebrae. One of the mostcommon fusion techniques utilized is the transforaminal lumbar interbodyfusion (TLIF) in which the intervertebral disc space is accessed andoperated on through a posterolateral approach. Generally, the TLIFprocedure is performed through an “open” approach requiring a largeincision and the separation and/or cutting of muscle and tissue,resulting in long recovery times and post-operative pain related to theprocedure. To reduce the drawbacks associated with open procedures,minimally invasive techniques that reduce incision size and musclecutting are becoming more popular. However, working through the smallerexposures brings other challenges, for example, decreased visualizationand decreased flexibility in manipulating surgical instruments, amongothers, and thus the skill, training, and experience required forperforming minimally invasive TLIF procedures is significantly higherthan for open surgeries. A need therefore exists for improvementsrelating to the performance of minimally invasive TLIF procedures. Theinstruments and methods described herein are directed to addressingthese needs.

SUMMARY

The present application describes implants, instruments, and methods forperforming surgical procedures on the spine, including one or more ofcreating an operative corridor to the spine, delivering implants to thespine, fusing one or more segments of the spine, and fixing one or moresegments of the spine.

According to one example, there is described a first method forattaching a fixation system to the spine of a patient. The fixationsystem includes at least two bone anchors and a spinal rod linking theat least two bone anchors. The method includes connecting a first boneanchor to a first retractor blade, advancing the first bone anchor andfirst retractor blade together to a first spinal bone, and anchoring thefirst bone anchor to the first spinal bone. The method also includesconnecting a second bone anchor to a second retractor blade, advancingthe second bone anchor and second retractor blade together to a secondspinal bone, and anchoring the second bone anchor to the second spinalbone. The method also includes connecting a retractor body to the firstretractor blade and the second retractor blade and operating theretractor body to expand an operative corridor formed between the firstretractor blade and second retractor blade from the skin level of thepatient to the spine. The method also includes linking the first boneanchor and the second bone anchor with a spinal rod.

According to another aspect of the first method the spinal bone is afirst vertebra and the second spinal bone is a second vertebra separatedfrom the first vertebra by an intervertebral disc space, and wherein thefirst spinal bone, second spinal bone, and intervertebral disc spacecomprise a first spinal level.

According to another aspect of the first method the first bone anchoredis anchored through a pedicle of the first vertebra and the second boneanchor is anchored through a pedicle of the second vertebra.

According to another aspect of the first method, the method may furtherinclude adjusting the angle of the operative corridor.

According to another aspect of the first method, the first method may beperformed wherein the angle of the operative corridor is adjusted untilthe operative corridor is parallel to the intervertebral disc space.

According to another aspect of the first method, adjusting the angle ofthe operative corridor is accomplished by moving a proximal end of thefirst retractor blade and a proximal end of the second retractor bladein the same direction while a distal end of the first retractor bladeremains in the same general position adjacent the first pedicle and adistal end of the second retractor blade remains in the same generalposition adjacent the second pedicle.

According to another aspect of the first method the angle of theoperative corridor is adjusted in one of a cephalad or caudal direction.

According to another aspect of the first method the angle of theoperative corridor is adjusted in one of an anterior and posteriordirection.

According to another aspect of the first method the angle of theoperative corridor is adjusted in both one of a cephalad and caudaldirection and in one of an anterior and posterior direction.

According to another aspect of the first method the first retractorblade is connected to the first bone anchor in a polyaxial engagementand the second retractor blade is connected to the second bone anchor ina poly axial engagement.

According to another aspect of the first method the first bone anchor isconnected to the first retractor blade via a first hoop shim slidablyengaged to an interior surface of said first retractor blade and thesecond anchor is connected to the second retractor blade by a secondhoop shim slidably engaged to an interior surface of said secondretractor blade.

According to another aspect of the first method each of the first hoopshim and the second hoop shim include a shim portion that slidablyengage the respective retractor blade and a hoop portion that receives ahead a respective bone anchor therethrough.

According to another aspect of the first method each of the first hoopshim and the second hoop shim have an unlocked configuration that allowsthe head of the respective bone screw to pass therethrough and a lockedconfiguration wherein the head of the respective bone screw is securedto the hoop shim.

According to another aspect of the first method the retractor body isfurther operated to distract the intervertebral disc space.

According to another aspect of the first method, the method may includeadvancing a third retractor blade towards the spine, connecting thethird retractor blade to the retractor body, and operating the retractorbody to expand the size of the operative corridor.

According to another aspect of the first method, the method may includeadvancing a third retractor blade towards the spine, connecting thethird retractor blade to the retractor body, and operating the retractorbody to further expand the size of the operative corridor.

According to another aspect of the first method the first and secondretractor blades expand the operative corridor in cranially and caudallyand the third retractor blade expands the operative corridor medially.

According to another aspect of the first method the third retractorblade clears tissue from the facet, lamina, and base of the spinousprocess as the third retractor blade retracted medially.

According to another aspect of the first method the third blade followsthe topography of the facet, lamina, and base of the spinous process asthe third retractor blade is retracted medially.

According to another aspect of the first method the third retractorblade includes a floating blade extension with a serrated distal endthat curves to form a concave backward facing lip.

According to another aspect of the first method, the method may includeapplying downward pressure to the floating blade extension of the thirdretractor blade as the third retractor blade is retracted medially tofacilitate clearing of the tissue from the facet, lamina, and base ofthe spinous process.

According to another aspect of the first method anchoring the first boneanchor to the first spinal bone comprises advancing a first anchorportion into said first spinal bone and subsequently attaching a firstreceiver portion to the first anchor portion and anchoring the secondbone anchor to the second spinal bone comprises anchoring a secondanchor portion to the second spinal bone and subsequently attaching asecond receiver portion to the second anchor portion.

According to another aspect of the first method the first anchor portionis connected to the first retractor blade via a first hoop shim having ashim element that slidably engages the first retractor blade and a hoopelement the secures the first anchor element, and wherein the secondanchor portion is connected to the second retractor blade via a secondhoop shim having a shim element that slidably engages the secondretractor blade and a hoop element the secures the second anchorportion.

According to another aspect of the first method, the method may includeremoving the first hoop shim from the first anchor portion prior toattaching the first receiver to the first anchor portion and removingthe second hoop shim from the second anchor portion prior to attachingthe second receiver to the second anchor portion.

According to another aspect of the first method, the method may includeoperating on the first spinal level through the operating corridor priorto linking the first bone anchor and the second bone anchor with thespinal rod.

According to another aspect of the first method operating on the firstspinal level includes one or more of a facetectomy, decompression,annulotomy, and discectomy.

According to another aspect of the first method at least a discectomy isperformed and an implant is inserted into the intervertebral space afterthe discectomy.

According to another aspect of the first method the implant ispositioned obliquely within the intervertebral space.

According to another aspect of the first method, the method may includeoperating the retractor body to distract the intervertebral disc spaceprior to performing the discectomy.

According to another aspect of the first method operating the retractorbody to distract the intervertebral space includes advancing a firstbolt disposed through a portion of the first retractor blade intocontact with the retractor body to prevent inward tilting of the firstretractor blade, advancing a second bolt disposed through a portion ofthe second retractor blade into contact with the retractor body toprevent inward tilting of the second retractor blade, and rotating aknob to increase the distance between a first arm of the retractor bodyengaged to the first retractor blade and a second arm of the retractorblade engaged to the second retractor blade.

According to another aspect of the first method the first retractorblade and the second retractor blade may be different lengths.

According to another aspect of the first method, the method may includeconnecting a third bone anchor to a fourth retractor blade, advancingthe third bone anchor and fourth retractor blade together to a thirdpedicle adjacent the second pedicle, anchoring the third bone anchor tothe third pedicle, and linking the third bone anchor together with thefirst bone anchor and second bone anchor with the spinal rod, whereinthe third pedicle is part of a third spinal bone separated from thesecond spinal bone by a second intervertebral disc space, and whereinthe second spinal bone, third spinal bone, and second intervertebraldisc space comprise a second spinal level.

According to another aspect of the first method the steps of connectinga third bone anchor to a fourth retractor blade, advancing the thirdbone anchor and fourth retractor blade together to a third pedicleadjacent the second pedicle, and anchoring the third bone anchor to thethird pedicle are performed after positioning the implant in theintervertebral disc space and before linking the first bone anchor,second bone anchor and third bone anchors with the spinal rod.

According to another aspect of the first method the first bone anchorincludes a first anchor portion and a first receiver that is attached tothe first anchor portion after the first anchor portion is anchored inthe first pedicle, the second bone anchor includes a second anchorportion and a second receiver that is attached to the second anchorportion after the second anchor portion is anchored in the secondpedicle, and the third bone anchor includes a third anchor portion and athird receiver that is attached to the third anchor portion after thethird anchor portion is anchored in the third pedicle.

According to another aspect of the first method the first anchor portionis connected to the first retractor blade via a first hoop shim having ashim element that slidably engages the first retractor blade and a hoopelement that secures the first anchor element, wherein the second anchorportion is connected to the second retractor blade via a second hoopshim having a shim element that slidably engages the second retractorblade and a hoop element that secures the second anchor portion, andwherein the third anchor portion is connected to the fourth retractorblade via a third hoop shim having a shim element that slidably engagesthe fourth retractor blade and a hoop element that secures the thirdanchor portion.

According to another aspect of the first method, the method may includedisconnecting the first retractor blade and the second retractor bladefrom the retractor body and reconnecting the retractor body to thesecond retractor blade and the fourth retractor blade and operating theretractor body to expand an operative corridor formed between the secondretractor blade and the fourth retractor blade from the skin level ofthe patient to the spine.

According to another aspect of the first method the second retractorblade includes multiple connector elements such that the secondretractor blade can be connected to the retractor body in bothright-facing and left-facing directions.

According to another aspect of the first method, the method may includedisconnecting the first retractor blade and the second retractor bladefrom the retractor body, replacing the second retractor blade with afifth retractor blade, and reconnecting the retractor body to the fifthretractor blade and the fourth retractor blade and operating theretractor body to expand an operative corridor formed between the fifthretractor blade and the fourth retractor blade from the skin level ofthe patient to the spine.

According to another aspect of the first method replacing the secondretractor blade with a fifth retractor blade includes the steps ofremoving the second retractor blade from a track insert connected to thesecond hoop shim and inserting the fourth retractor blade over the trackinsert.

According to another aspect of the first method, the method may includeengaging a track guide to the track insert before removing the secondretractor blade and inserting the fifth retractor blade along the trackguide to facilitate engagement of the fifth retractor blade with thetrack insert.

According to another aspect of the first method, the method may includeoperating on the second spinal level through the operating corridorprior to linking the first bone anchor, second bone anchor, and thirdbone anchor with the spinal rod.

According to another aspect of the first method operating on the secondspinal level includes performing one or more of a facetectomy,decompression, annulotomy, and discectomy.

According to another aspect of the first method at least a discectomy isperformed and a second implant is inserted into the secondintervertebral space after the discectomy.

According to another aspect of the first method a second implant ispositioned obliquely within a second intervertebral space.

According to another aspect of the first method, the method may includeoperating the retractor body expand the operating corridor to reexposethe first bone anchor, disconnecting the second anchor portion and fifthblade, disconnecting the third anchor portion and fourth blade, andattaching the first receiver to the first anchor portion, attaching thesecond receiver to the second anchor portion, and attaching the thirdreceiver to the third anchor portion, prior to linking the first boneanchor, second bone anchor, and third bone anchor with the spinal rod.

According to another example, there is described a second method forperforming a spinal fusion procedure on a spinal segment of a humanspine, the spinal segment including at least a first vertebra and asecond vertebra separated from the first vertebra by an intervertebraldisc space, including the steps of (a) anchoring a first anchor portionto a first pedicle, the first anchor portion being connected to a firstretractor blade of a retractor assembly; (b) anchoring a second anchorportion to a second pedicle, the second anchor portion being connectedto a second retractor blade of the retractor assembly; (c) connectingthe first retractor blade to a first arm of a retractor body of theretractor assembly and connecting the second retractor blade to a secondarm of the retractor body; (d) operating the retractor body to increasethe distance between the first arm and the second arm to expand anoperating corridor between the first retractor blade and the secondretractor blade; (e) advancing a third retractor blade through theoperative corridor to the spinal segment; connecting the third retractorblade to a translating arm of the retractor body, and operating theretractor body to translate the translating arm and further expand thesize of the operating corridor; (f) preparing the intervertebral discspace to receive an implant; (g) implanting a fusion implant in theintervertebral disc space; (h) disconnecting the first retractor bladefrom the first anchor portion and attaching a first receiver portion tothe first anchor portion; (i) disconnecting the second retractor bladefrom the second anchor portion and attaching a second receiver portionto the second anchor portion; (j) inserting and locking a rod into thefirst receiver portion and second receiver portion; and (k) removing thefirst and second retractor blades from the operative corridor andclosing the operative corridor.

According to another aspect of the second method the first anchorportion is connected to the first retractor blade via a hoop shimslidably engaged with the first retractor blade.

According to another aspect of the second method the second anchorportion is connected to the second retractor blade via a hoop shimslidably engaged with the second retractor blade.

According to another aspect of the second method, the method may includeconnecting the first anchor portion to the first retractor blade byinserting a head of the first anchor portion into a hoop member of thehoop shim and engaging a shim element of the hoop shim to the firstretractor blade and connecting the second anchor portion to the secondretractor blade by inserting a head of the second anchor portion into ahoop element of a hoop shim and engaging a shim element of the hoop shimto the second retractor blade.

According to another aspect of the second method engaging a shim elementof a hoop shim to one of the first and second retractor blades includesinserting the shim element into a track formed along an interior face ofthe retractor blade and sliding the shim element down the track untilthe shim element sits in a distal most position along the track.

According to another aspect of the second method stops at the distal endof the track prevent the hoop shim from disengaging the retractor bladefrom the distal end of the blade.

According to another aspect of the second method, may includemanipulating the hoop shim connected to one of the first and secondanchor portions into a locked configuration that prevents disassociationof the anchor portion and the hoop shim.

According to another aspect of the second method manipulating the hoopshim into a locked position includes slidably advancing a hoop portionof the hoop shim towards the shim element.

According to another aspect of the second method slidably advancing thehoop portion towards the shim element causes a flange of the hoopportion to deflect inwards which causes a dimension of an anchor headreceiving aperture in the hoop member to decrease.

According to another aspect of the second method the hoop shim ismanipulated into the locked position after the hoop shim is insertedinto a track formed along an interior face of one of the first andsecond retractor blades and advanced down the track to a distal end ofthe retractor blade.

According to another aspect of the second method may include connectingan inserter to the one of the first bone anchor first retractor bladeand second bone anchor second retractor blade combinations

According to another aspect of the second method the shim elementsslidably engage.

According to another example, a first system includes a retractor forperforming and creating an operative corridor to a surgical target siteis described. The system includes a retractor body which includes afirst arm; a second arm, the first arm and the second arm being movablerelative to each other in a first direction; and a center arm movablerelative to the first arm and the second arm in a second directionorthogonal to the first direction; a first retractor blade attachable tofirst arm; a second retractor blade attachable to the second arm; and athird retractor blade attachable to the center arm, wherein the thirdretractor blade is pivotable relative to the center arm in the firstdirection.

According to another aspect of the first system the first and secondretractor blades are registerable to first and second pedicle of thespine.

According to another aspect of the first system the first and secondretractor blades are registerable to the spine via a poly axialengagement.

According to another aspect of the first system the poly axialengagement is with a hoop shim.

According to another example, a second system for creating an operativecorridor to a surgical target site is described. The second systemincludes a retractor body, the retractor body including a first arm; asecond arm, the first arm and the second arm being movable relative toeach other in a first direction; and a center arm movable relative tothe first arm and the second arm in a second direction orthogonal to thefirst direction. The second system also includes a first retractor bladeattachable to first arm; a second retractor blade attachable to thesecond arm; and a third retractor blade attachable to the center arm,wherein a distal end of the first retractor blade is configured to betemporarily anchored in position relative to a first spinal bone and aproximal end of the first retractor blade is pivotable relative to thefirst arm, and wherein a distal end of the first retractor blade isconfigured to be temporarily anchored in position relative to a secondspinal bone and a proximal end of the second retractor blade ispivotable relative to the second arm.

According to another example, a third system is described including ahoop shim for use with a surgical tissue retractor system. The hoop shimincludes a shim portion having at least one feature that releasablyassociates with a retractor blade of the surgical retractor system; anda hoop portion having a hoop member that releasably associates with thehead of a bone anchor.

According to another aspect of the third system the hoop portion and theshim portion are slidably engaged.

According to another aspect of the third system the hoop member extendsorthogonally to the shim portion.

According to another aspect of the third system the hoop member has anunlocked position which allows passage of the bone anchor head and alocked position which prevents passage of the bone anchor head.

According to another aspect of the third system the shim portion and thehoop portion are slidably engaged and the locked position is entered bysliding the hoop portion towards a proximal end of the shim portion.

According to another aspect of the third system sliding the hoop portiontowards the proximal end of the shim portion causes a dimension of anaperture formed through the hoop member to decrease in size.

According to another aspect of the third system the hoop portionincludes a first flange and a second flange extending from the hoopmember.

According to another aspect of the third system the first flange slideswithin a recess formed in the back of the shim element.

According to another aspect of the third system the first flange has awing extension along at least portion of the first flange extendingbeyond a perimeter of the recess in the back of the shim element, thewing extension being receivable within a track groove of the retractorblade.

According to another aspect of the third system the second flange alsoslides within the recess formed in the back of the shim element.

According to another aspect of the third system the second flangeincludes a proximal portion having a first width and an intermediateportion having a width greater than the first width of the proximalportion.

According to another aspect of the third system the proximal portionalways resides within the recess in the back of the shim element.

According to another aspect of the third system the intermediate portionresides outside the recess when the hoop portion is in the unlockedposition and resides in the recess when the hoop portion is in thelocked position.

According to another aspect of the third system the intermediate portionhas a sloped upper surface that engages a knob situated at the entrancesuch that second flange deflects toward the first flange when the hoopportion slides into the recess.

According to another aspect of the third system deflection of the secondflange causes a dimension of an aperture formed through the hoop memberto decrease in size.

According to another aspect of the third system deflection of the secondflange causes a slight rotation of the shim element relative to thefirst flange such that a distal end of the shim element flares out tothe side opposite the first flange and such that a width between thedistal end of a wing extension on the first flange and distal end of awing extension on the shim element is greater than the width at anentrance between a first track groove and a second track groove of theretractor blade thereby preventing the hoop shim from being slidablyengaged to the retractor blade when the hoop shim is locked.

According to another aspect of the third system the intermediate portionhas bottom portion sloped in the opposite direction of the slopped topportion that permits the intermediate portion to slide out of therecess.

According to another aspect of the third system the bottom surface issteeper than the slope of the top surface.

According to another aspect of the third system the sloped top surfaceof the intermediate element is also concave.

According to another aspect of the third system the sloped bottomsurface of the intermediate element is also convex.

According to another aspect of the third system the first flangeincludes a tab disposed through a slot formed in the shim portion.

According to another aspect of the third system a retaining plate on thetab fixes the hoop portion and the shim portion together.

According to another aspect of the third system the hoop member includesan insert.

According to another aspect of the third system the insert comprises apolymer material.

According to another aspect of the third system the polymer ispolyetheretherkeytone.

According to another aspect of the third system when the hoop portion isreleasably associated with the bone anchor, the association permits thebone anchor to angularly move relative to the hoop portion.

According to another aspect of the third system the association permitspolyaxial angulation.

According to another aspect of the third system the polyaxial angulationencompasses 360 degrees.

According to another aspect of the third system the shim portion and thehoop portion are provided preassembled.

According to another aspect of the third system the shim portion has ahorizontal slot formed near a proximal end.

According to another aspect of the third system the horizontal slot hasa ramped back-facing surface.

According to another example, a fourth system is described including aretractor blade for use with a surgical tissue retractor system. Theretractor blade includes an attachment portion, an upper blade portionthat extends generally orthogonally from the attachment portion, and alower blade portion that extends at an obtuse angle from the upperportion such that a distal end of the lower blade portion is offset fromthe plane of the upper portion.

According to another aspect of the fourth system the distal end of thelower portion is offset from the plane of the upper portion byapproximately one-quarter inch.

According to another aspect of the fourth system the retractor blade isprovided in multiple lengths and the angle at which the lower bladeportion extends from the upper blade portion is varied to achieve agenerally uniform offset.

According to another aspect of the fourth system the lower blade portionhas a greater width than the upper blade portion.

According to another aspect of the fourth system the lower blade portionincludes a free sliding blade extension.

According to another aspect of the fourth system the lower blade portionhas a recess in which the free sliding blade extension slides.

According to another aspect of the fourth system the recess has anelongated central slot in which a guide extension of the blade extensionis disposed.

According to another aspect of the fourth system the recess alsoincludes side grooves in which the edges of the blade extension arereceived.

According to another aspect of the fourth system the length of thecentral slot determines the sliding distance of the blade extension.

According to another aspect of the fourth system the distal end of theblade extension is curved toward the exterior side of the retractorblade.

According to another aspect of the fourth system the distal end of theblade extension is also has a concave curve.

According to another aspect of the fourth system the edge of the distalend is serrated.

According to another aspect of the fourth system the attachment portionincludes an engagement feature that pivotally engages a retractor body.

According to another aspect of the fourth system the engagement featureis a cylindrical aperture dimensioned to receive a cylindrical post ofthe retractor body.

According to another aspect of the fourth system the attachment portionincludes a set screw extending into the cylindrical aperture to securethe retractor blade to the retractor body.

According to another aspect of the fourth system the attachment portionincludes a second engagement feature that connects to an insertionhandle.

According to another aspect of the fourth system the second engagementfeature is a post with a tapered proximal end and a cylindrical groovethat is configured to receive a coil spring that extends into in acylinder dimensioned to receive the post.

According to still another example there is described a fifth system,the fifth system including an inserter for anchoring a bone anchor. Theinserter includes a driver assembly having a driver shaft and a distalengagement feature that engages a drive feature of the bone anchor; anda blade engagement member that releasably engages a retractor blade of aretractor assembly.

According to another aspect of the fifth system the driver shaft freelyrotates relative to the engagement member such that a retractor bladeattached to the engagement member doesn't rotate with the bone anchor asthe bone anchor is driven into bone.

According to another aspect of the fifth system the blade engagementmember comprises a body with a pair of wing extensions that slidablyengage a pair of track grooves along the interior face of the retractorblade.

According to another aspect of the fifth system the engagement memberfurther comprises a deflectable tab configured to be received withinnotches in the retractor blade.

According to another aspect of the fifth system the system furthercomprises a receiver member that captures a head of the bone anchor.

According to another aspect of the fifth system the receiver membercomprises a receptacle having deflectable flanges that deflect inwardaround the head of the bone anchor to secure the bone anchor to thereceiver member.

According to another aspect of the fifth system a thumb wheel linked tothe receiver member draws the deflectable fingers into a cylindercausing the fingers to deflect.

According to another aspect of the fifth system the distal engagementfeature of the driver shaft is housed within the receptacle such thatthe distal engagement feature engages with the drive feature of the boneanchor head when the bone anchor head is secured in the receptacle.

According to another aspect of the fifth system the receptacle rotateswith the driver shaft.

According to another aspect of the fifth system the driver shaft iscannulated.

According to another example there is described a sixth system includinga bone anchor, a retractor blade, and a shim that can be assembled intoan anchor-blade-shim assembly. The sixth system includes a bone anchorhaving an anchor portion that includes a partially spherical head; aretractor blade that is attachable to a retractor assembly, theretractor blade having a track including first and second track groovesformed in an interior face; and a shim that slidably engages the firstand second track grooves such that it is advanceable down the tracktowards a distal end of the retractor blade and securely engages thepartially spherical head of the bone anchor in a polyaxial engagement.

BRIEF DESCRIPTION OF THE DRAWINGS

Many advantages of the present invention will be apparent to thoseskilled in the art with a reading of this specification in conjunctionwith the attached drawings, wherein like reference numerals are appliedto like elements and wherein:

FIG. 1 is a perspective view of an example of a surgical fixation systemaccording to one embodiment of the present invention;

FIG. 2 is an exploded perspective view of the surgical fixation systemof FIG. 1;

FIGS. 3-5 are front, perspective, and side views of the surgicalfixation system of FIG. 1;

FIG. 6 is a partially exploded perspective view of an example of atissue retraction system forming part of the surgical fixation system ofFIG. 1;

FIG. 7 is an exploded perspective view of an example of a retractor bodyforming part of the tissue retraction system of FIG. 6;

FIG. 8 is a front perspective view of the retractor body of FIG. 7;

FIGS. 9-10 are front perspective and rear perspective views,respectively, of an example of a housing member forming part of theretractor body of FIG. 7;

FIG. 11 is a top perspective view of the retractor body of FIG. 8 withthe housing member removed;

FIG. 12 is a top plan view of an example of a rack member forming partof the retractor body of FIG. 7;

FIG. 13 is a perspective view of the rack member of FIG. 12 with thesecond rack member removed;

FIG. 14 is an exploded perspective view of a first toggle forming partof the retractor body of FIG. 7;

FIGS. 15-16 are top plan and perspective views, respectively, of amedial retraction member coupled with a second toggle, forming part ofthe retractor body of FIG. 7;

FIG. 17 is an exploded perspective view of a second toggle forming partof the retractor body of FIG. 7;

FIGS. 18-19 are perspective views of an example of first arm memberforming part of the retractor body of FIG. 7;

FIGS. 20-21 are perspective views of an example of a second arm memberforming part of the retractor body of FIG. 7;

FIGS. 22-25 are various plan views of an example of a retractor bladeassembly forming part of the tissue retraction system of FIG. 6;

FIG. 26 is an exploded view of the retractor blade assembly of FIG. 22;

FIGS. 27-30 are front plan, perspective, rear perspective, and side planviews, respectively, of a medial retractor blade assembly forming partof the tissue retraction system of FIG. 6;

FIGS. 31-34 are perspective, exploded perspective, rear plan, and topplan views, respectively, of an example of a hoop shim assembly formingpart of the surgical fixation system of FIG. 1, the hoop shim assemblyshown in an unlocked position;

FIGS. 35-37 are front plan, side plan and top plan views, respectively,of the hoop shim assembly of FIG. 31 in a locked position and engaged toa bone anchor forming part of the surgical fixation system of FIG. 1;

FIG. 38 is a front plan view of the hoop shim assembly of FIG. 31 beingcoupled to a retractor blade assembly of FIG. 22;

FIG. 39 is a front plan view of the hoop shim assembly locked andengaged with the bone anchor of FIG. 35 coupled to a retractor bladeassembly of FIG. 22;

FIGS. 40-41 are perspective and side plan views, respectively, of anexample of a hoop shim removal tool according to one embodiment of thepresent invention;

FIG. 42 is a side plan view of a distal engagement region forming partof the hoop shim removal tool of FIG. 40;

FIGS. 43-45 are font plan, back plan, and side plan views, respectively,of the hoop shim assembly locked and engaged with the bone anchor ofFIG. 35 coupled to a retractor blade assembly of FIG. 22, and alsocoupled to the hoop shim removal tool of FIG. 40 prior to disengagementof the hoop shim assembly from the bone anchor;

FIG. 46 is a perspective view of the hoop shim assembly unlocked anddisengaged from the bone anchor of FIG. 35 coupled to a retractor bladeassembly of FIG. 22, and also coupled to the hoop shim removal tool ofFIG. 40 after disengagement of the hoop shim assembly from the boneanchor;

FIGS. 47-48 and 50-53 are perspective views of the surgical fixationsystem of FIG. 1 during different stages of use on a spinal segment;

FIG. 49 is a top plan view of the fully assembled surgical fixationsystem of FIG. 1;

FIGS. 54 and 55 are front plan and perspective views, respectively, ofthe fully assembled surgical fixation system of FIG. 1 in use on aspinal segment, particularly illustrating the extreme angulationcapability of the system;

FIG. 56 is the front plan view of the fully assembled surgical fixationsystem of FIG. 49 with the spinal segment removed;

FIG. 57 is a close-up plan view of the fully assembled surgical fixationsystem of FIG. 49, illustrating in particular the lockability of thesystem in an extreme angulation state;

FIGS. 58-61 are perspective views of a locked hoop shim assembly andbone anchor combination of FIG. 35, with the bone anchor implantedwithin a bony segment, illustrating in particular the polyaxialengagement between the hoop shim assembly and bone anchor;

FIGS. 62 and 63 are front plan and perspective views, respectively, ofthe tissue retraction system of FIG. 6 having retractor blades ofdifferent lengths;

FIG. 64 is a perspective view of an example of an inserter according toone embodiment of the present invention, coupled to a bone anchor andhoop shim assembly of FIG. 35 and retractor blade of FIG. 22;

FIG. 65 is a perspective view of a distal region of the inserter, boneanchor, hoop shim assembly, and retractor blade combination of FIG. 64;

FIG. 66 is a perspective view of the inserter of FIG. 64;

FIG. 67 is an exploded perspective view of the inserter of FIG. 64;

FIGS. 68-70 are plan, perspective, and sectional views, respectively, ofa receiver member forming part of the inserter of FIG. 64;

FIGS. 71 and 72 are perspective views of a distal end of a receiverassembly forming part of the inserter of FIG. 64;

FIG. 73 is a perspective view of a receiver assembly forming part of theinserter of FIG. 64;

FIG. 74 is a perspective view of a driver member forming part of theinserter of FIG. 64;

FIG. 75 is a perspective view of a distal end of the driver member ofFIG. 74;

FIG. 76 is a perspective view of a distal end of the driver member ofFIG. 74 coupled with the receiver assembly of FIG. 71;

FIG. 77 is a perspective view of a distal end of the driver member ofFIG. 74 coupled with the receiver assembly of FIG. 72;

FIG. 78 is a perspective view of a blade engagement assembly formingpart of the inserter of FIG. 64;

FIG. 79 is a perspective view of an example of a hoop shim reattachmenttool according to one embodiment of the present invention;

FIG. 80 is an exploded perspective vie w of the hoop shim reattachmenttool of FIG. 79;

FIG. 81 is a side cross-section view of the hoop shim reattachment toolof FIG. 79;

FIG. 82 is an enlarged perspective view of the distal end region of thehoop shim reattachment tool of FIG. 79;

FIG. 83 is a perspective view of the distal end of a light cable,according to one example embodiment of the present invention;

FIG. 84 is a perspective view of the distal end of the light cable ofFIG. 83 engaged to the retractor blade of FIG. 22 and extending over theproximal end of the hoop shim of FIG. 31;

FIG. 85 is a perspective view of a tissue shim according to one exampleembodiment of the present invention;

FIG. 86 is a perspective view of the tissue shim of FIG. 86 illustratingthe manner in which the shim element of the hoop shim nestles betweenwings of the tissue shim;

FIG. 87 is a front view of an alternate retractor blade for use with thesurgical fixation system of FIG. 1, according to one example embodiment;

FIG. 88 is a front view of the retractor blade of FIG. 87 with a trackinsert removed;

FIG. 89 is a front view of a track insert forming part of the retractorblade of FIG. 87;

FIG. 90 is a front view of the retractor blade of FIG. 87 with the hoopshim of FIG. 31 engaged;

FIG. 91 is a front view of the track insert of FIG. 90 with the hoopshim engaged and the remainder of retractor blade removed;

FIG. 92 is a perspective view of a guide instrument for use with theretractor blade of FIG. 87, according to one example embodiment;

FIG. 93 is an exploded perspective view of the guide instrument of FIG.92

FIG. 94 is a perspective view of the distal end of the body portion ofthe guide instrument of FIG. 92;

FIG. 95 is a perspective view of an actuator of the guide instrument ofFIG. 92;

FIG. 96 is a perspective view of the distal end of a driver of the guideinstrument of FIG. 92;

FIG. 97 is a perspective view of the housing forming part of the bodyportion of FIG. 94;

FIG. 98 is a cross section view of the housing of FIG. 97 showing theactuator of FIG. 95 and the driver of FIG. 98 interacting therein;

FIG. 99 is a perspective view of the guide instrument of FIG. 92 engagedto the retractor blade and track insert of FIG. 87;

FIG. 100 is an enlarged view of the distal end of the guide instrumentof FIG. 92 engaged to the retractor blade and track insert of FIG. 87;and

FIG. 101-108 are perspective view of the spinal fixation system of FIG.1 including the retractor blade of FIG. 87 in use during various stepsof a multi-level spinal fusion procedure.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Illustrative embodiments of the invention are described below. In theinterest of clarity, not all features of an actual implementation aredescribed in this specification. It will of course be appreciated thatin the development of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure. The systems and methods for performing transforaminallumbar interbody fusion disclosed herein boast a variety of inventivefeatures and components that warrant patent protection, bothindividually and in combination.

FIGS. 1-5 illustrate an example of a surgical fixation system 5according to one embodiment of the present invention. The surgicalfixation system 5 includes a variety of sub-components dimensioned toallow for retraction of a soft tissue in order to establish an operativecorridor through a patient's skin to a surgical target site. By way ofexample only, the surgical target site referred to herein throughout isan intervertebral disc space situated between two adjacent vertebrae.Although particularly suited for use in lumbar spine fixation, it willbe readily appreciated by those skilled in the art that the surgicalfixation system of the present invention may be employed in any numberof suitable orthopedic fixation approaches and procedures, including butnot limited to anterior, posterior, lateral, anterolateral,posterolateral, cervical spine fixation, thoracic spine fixation, aswell as any non-spine fixation application such as bone fracturetreatment.

By way of example only, the surgical fixation system 5 includes a tissueretraction assembly 10, a plurality of hoop shims 6, and a plurality ofbone anchors 7. According to one broad aspect of the present invention,the tissue retraction system 10 includes retractor body 12, a firstretractor blade 14, a second retractor blade 16, and a third retractorblade 18 (also referred to herein throughout as the medial blade 18).The retractor blades 14, 16, 18 may be provided in any size and shapesuitable to establish and maintain an operative corridor to the surgicaltarget site, however, certain benefits may be achieved utilizing one ormore aspects of the various shaped retractor blades described, whichfeatures should be apparent from the discussion herein. The bone anchor7 may be one of the type shown and described in U.S. patent applicationSer. No. 12/820,136, filed Jun. 21, 2010 and entitled “Polyaxial BoneScrew Assembly,” the entire contents are hereby incorporated byreference into this disclosure as if set forth fully herein.

The tissue retraction assembly 10 may be configured such that theretractor blades 14, 16, 18 may be advanced to the surgical target siteindividually (e.g. sequentially) or together (e.g. simultaneously). Forexample, for simultaneous advancement, two or more of the retractorblades 14, 16, 18 may be attached to the retractor body prior toadvancement to a surgical target site. As will be explained by way ofexample in further detail below, the tissue retraction assembly 10 isparticularly suitable for individual advancement of each blade 14, 16,18 to a surgical target site. For instance, the first retractor blade 14may be advanced through an incision and securely attached to a firstbone segment within the surgical target site. The second retractor blade16 may then be advanced through an incision and securely attached to asecond bone segment within the surgical target site. Once the first andsecond retractor blades 14, 16 are secured to the first and second bonesegments, the retractor blades 14, 16 may then be attached to theretractor body 12. Thereafter, the first and second retractor blades 14,16 may be further moved by the retractor assembly to a second “open”position to establish and maintain a second operative corridor (orworking channel). This operative corridor may be variable in size andapproach angle to the surgical target site, providing the ability toestablish numerous custom working channels. The medial retractor blade18 may then be attached to the retractor body 12 and used as desired.

Referring to FIGS. 6-8, the retractor body portion 12 includes a housingmember 20, a rack member 22, a medial retraction member 24, a firstretractor arm 26, a second retractor arm 28, a first toggle 30, and asecond toggle 32. Broadly, the housing member 20 provides a scaffold tohold the various components together. The rack member 22 provides amechanism to expand the operative corridor in a caudal-cranial directionby moving the retractor blades 14, 16 toward or away from one another.The medial retraction member 24 provides a mechanism to expand theoperative corridor in a medial direction by moving the medial retractorblade 18 away from the first and second retractor blades 14, 16. Thefirst retractor arm 26 couples to the first retractor blade 14, and aswill be explained in detail below, is configured to enable the firstretractor blade 14 to retract nearby soft tissue and/or distract thefirst bone segment. The second retractor arm 28 couples to the secondretractor blade 16, and is configured to enable the second retractorblade 16 to retract nearby soft tissue and/or distract the second bonesegment. The first toggle 30 controls the caudal-cranial movement of thefirst and second retractor arms 26, 28, and therefore the first andsecond retractor blades 14, 16. The second toggle 32 controls the medialmovement of the medial retraction member 24, and therefore the medialblade 18.

Referring now to FIGS. 9-10, the housing member 20 has a front side 34,a back side 36, an upper portion 38, and a lower portion 40. The housingmember 20 further includes a first recess 42 extending axially throughthe upper portion 38 from the front side 34 to the back side 36. Thefirst recess 42 is configured to receive the medial retraction member 24therein. The first recess 42 include a pair of track grooves 44 that areconfigured to engage with flanges 110, 112 on the medial retractionmember 24 to secure the medial retraction member to the housing 20. Thefirst recess 42 further includes a tapered surface 46 extending from thefront side of the first recess 42 toward the front side 34 of thehousing member 20. This tapered surface 46 enables medial-lateralangulation of the medial retraction member 24 while in a retractedposition. The tapered surface 46 is flanked by a pair of curved surfaces48 that enable caudal-cranial pivoting of the medial retraction member24 while in a retracted position. The upper portion 38 further includesa second recess 50 and a third recess 52, formed within the housingmember 20 on either side of the first recess 42. The second recess 50 isconfigured to receive the first toggle 30 therein. The second recess 50is dimensioned to allow for movement of the toggle 30 therein to enablethe toggle 30 to perform its function, which is explained in furtherdetail below. The third recess 52 is configured to receive the secondtoggle 32 therein. The third recess 52 is dimensioned to allow formovement of the toggle 32 therein to enable the toggle 32 to perform itsfunction, which is explained in further detail below. The upper portion38 further includes at least one attachment member 53 dimensioned toenable attachment of the retractor body 12 to an articulating arm (notshown) within the operative field. This attachment to the articulatingarm ensures that the surgical retraction system 10 is securelyregistered to the operating table. The upper portion may also beprovided with at least one aperture 55 dimensioned to receive a tool(not shown) configured to allow the operator to alter the position ofthe retractor body 12 in order to adjust the angle of the operativecorridor.

The lower portion 40 includes a first lumen 54 extending axially throughthe housing member 20 transverse to the first recess 42. By way ofexample only, the first lumen has a generally rectangular cross-sectionand is configured to slideably receive the first rack member 58therethrough. The lower portion 40 further includes a second lumen 56extending axially through the housing member 20 transverse to the firstrecess 42 and parallel to the first lumen 54. By way of example only,the second lumen 56 has a generally rectangular cross section and isconfigured to slideably receive the second rack member 60 therethrough.

FIG. 11 illustrates the retractor body 12 without the housing member 20to provide a clear view of the rack 22. Referring now to FIG. 12, therack 22 includes a first rack member 58 and a second rack member 60. Byway of example only, the first rack member 58 is an elongated axialmember having a generally rectangular cross section and a first end 62,a second end 64, and an elongated body 66 extending therebetween.Although shown and described as generally rectangular, other crosssectional shapes are possible without departing from the scope of thepresent invention. The first rack member 58 is dimensioned to beslideably received within the first lumen 54 of the housing member 20.The first end 62 is connected to the first retractor arm 26. The firstrack member 58 further includes a plurality of teeth 68 on one surface,the teeth being provided along substantially the length of the firstrack member 58. The teeth interact with the first toggle 30 to allowcontrolled caudal-cranial movement of the first retractor blade 14, aswill be described.

By way of example only, the second rack member 60 is an elongated axialmember having a generally rectangular cross section and a first end 70,a second end 72, and an elongated body 74 extending therebetween.Although shown and described as generally rectangular, other crosssectional shapes are possible without departing from the scope of thepresent invention. The second rack member 60 is dimensioned to beslideably received within the second lumen 56 of the housing member 20.The first end 70 is connected to the second retractor arm 28. The secondrack member 60 further includes a plurality of teeth 76 on one surface,the teeth being provided along substantially the length of the secondrack member 60. The teeth interact with the first toggle 30 to allowcontrolled caudal-cranial movement of the second retractor blade 16, aswill be described.

Referring to FIGS. 7 and 13-14, the first toggle 30 includes an actuator78, a gear 80, and a release member 82. The actuator 78 includes asuperior handle portion 84 that includes a friction feature that enablesa user to grip and turn the handle portion 84. By way of example only,the handle portion 84 is provided with a friction feature comprising aplurality of planar surfaces 86 (for engagement with a rotation handle),however other friction features are possible, for example ridges, knobs,dimples, and/or a material overlay such as rubber that provides foradequate gripping by a user. The actuator 78 further includes aninferior post 88 that extends away from the handle portion 84. Theinferior post 88 includes at least one generally planar surface 90configured to mate with the planar surface 93 of the gear 80 andtransfer the torque applied by a user to the handle portion 84 to thegear 80, thus turning the gear 80. The inferior post 88 further includesa recess 92 for receiving a snap ring 95, which functions to secure thefirst toggle 30 to the housing member 20.

By way of example only, the gear 80 has a generally circularcross-section and includes a central lumen 91 extending therethrough anda plurality of teeth 94 in the form of vertical ridges distributed aboutthe perimeter of the gear 80. The central lumen 91 includes a planarsurface 93 configured to mate with the planar surface 90 of the actuator78 to transfer the torque applied by a user to the handle portion 84 tothe gear 80, thus turning the gear 80. The teeth 94 of the gear 80 areconfigured to mate with the teeth 68, 76 of the first and second rackmembers 58, 60. As shown by way of example in FIG. 12, the first toggle30 is positioned between the first and second rack members 58, 60 suchthat the teeth 94 of the gear 80 simultaneously engages the teeth 68 ofthe first rack member 58 and the teeth 76 of the second rack member 60.Thus, as the handle portion 84 of the actuator 78 is turned by a user,the gear 80 causes the first and second racks 58, 60 to simultaneouslymove in opposite directions. For example, when the handle portion 84 isrotated in a clockwise direction, the first rack 58 will move in acranial direction (assuming proper placement of the retractor relativeto the spine) and the second rack 60 will move in a caudal direction.The effect of this movement is that the first retractor blade 14,through its connection to the first arm 26 (which is connected to thefirst rack member 58) will move in a cranial direction and the secondretractor blade 16, through its connection to the second retractor arm28 (which is connected to the second rack member 60) will movesimultaneously in a caudal direction.

Referring again to FIGS. 7 and 13-14, the release member 82 includesbody 96, a tab 98, and a flange 100. The body 96 is a generally circularmember having a central lumen 102 extending therethrough. The centrallumen 102 is dimensioned to receive the post 88 of the actuator 78. Thetab 98 extends radially from the body and functions as a manipulationpoint for the user. The flange 100 includes a ratchet member 104 that isdimensioned to interact with the teeth 68 of the first rack member 58.The release member 82 further includes a spring 106 that biases theratchet member 104 into an engaged position relative to the teeth 68.Thus, as the gear 80 turns and the first rack member 58 moves, theratchet member 104 clicks into engagement with each passing tooth 68.Thus the ratchet member 104 provides for controlled translation of thefirst and second rack members 58, 60, and creating a customizableoperative corridor established in incremental amounts. The ratchetmember 104 further prevents unwanted migration of the first rack member58 (and therefore the second rack member 60 as well) such that thedesired operative corridor will not alter once established. The ratchetmember 104 is configured to allow for unidirectional movement of thefirst rack member 58 relative thereto while the ratchet member 104 isengaged to the gear 80. The ratchet member 104 effectively preventscounterclockwise turning of the handle member 84. To contract theoperative corridor, for example upon completion of the desired surgicalprocedure, the user activates the tab 98, causing the ratchet member 58to disengage from the teeth 68. This allows for free (though stillsimultaneous) translation of the first and second rack members relativeto the housing member 20. That is, a counterclockwise turning of thehandle member 84 will cause the first and second rack members 58, 60 totranslate in an opposite direction, such that the first retractor blade14 will move in a caudal direction and the second retractor blade 16will move in a cranial direction.

FIGS. 15-17 illustrate the medial retraction member 24 in greaterdetail. By way of example only, the medial retraction member 24comprises a medial rack 108 dimensioned to fit in the first recess 42 ofthe housing member 20. By way of example only, the medial rack 108 is anelongated axial member having a generally rectangular cross section. Themedial rack 108 includes a first flange 110 and a second flange 112,each extending the length of the medial rack 108 and dimensioned toengage the overhangs 44 of the first recess 42. The first flange 110includes a plurality of teeth 114 in the form of vertical ridges thatare distributed along the length of the first flange 110. The teeth 114engage with the gear 124 of the second toggle 32 to enable movement ofthe medial rack 108. The medial rack 108 further includes a post 116extending axially from the front end of the medial rack 108. The post116 is configured for engagement with the medial blade 18. The post 116has an end portion 118 having a first diameter and a recessed portion120 between the end portion 118 and the medial rack 108, the recessedportion 120 having a reduced diameter relative to the end portion 118.This configuration allows for engagement, for example a snap-fitengagement, with the medial blade 18.

The medial rack further includes at least one attachment member 109dimensioned to enable attachment of the medial retraction member 24 toan articulating arm (not shown) within the operative field. Thisattachment to the articulating arm ensures that the surgical retractionsystem 10 is securely registered to the operating table. The attachmentmember 109 on the medial retraction member 24 is structurally identicalto, and performs the same function as, the attachment member 53 of thehousing member 20 (FIGS. 10-11). However, attachment to the attachmentmember 109 of the medial retraction member 24 provides an entirelydifferent effect than attachment to the attachment member 53 of thehousing member 20. Specifically, attachment to the attachment member 109registers the medial retraction member 24 to the articulating arm, andtherefore the surgical table. In this state, the medial retractionmember 109 is secured in place, and actuation of the toggle 32 willtherefore cause the retractor body 12, to move laterally relative to thepatient. Conversely, when the articulating arm is attached to theattachment member 53 of the housing 20, the housing 20 is secured inplace relative to the operating table, the actuation of the toggle 32will cause the medial retraction member 24 to move medially relative tothe patient. This feature is advantageous in situations in which themedial blade 18 has been placed, but for some reason the surgeon wouldprefer to move the operative corridor laterally relative to the spinerather than medially.

Referring now to FIG. 7 in addition to FIGS. 15-17, the second toggle 32includes an actuator 122, a gear 124, and a release member 126. Theactuator 122 includes a superior handle portion 128 that includes afriction feature that enables a user to grip and turn the handle portion128. By way of example only, the handle portion 128 is provided with afriction feature comprising a plurality of planar surfaces 130, howeverother friction features are possible, for example ridges, knobs,dimples, and/or a material overlay such as rubber that provides foradequate gripping by a user. The actuator 122 further includes aninferior post 132 that extends away from the handle portion 128. Theinferior post 132 includes at least one generally planar surface 134configured to mate with the planar surface 127 of the gear 124 andtransfer the torque applied by a user to the handle portion 128 to thegear 124, thus turning the gear 124. The inferior post 132 furtherincludes a recess 136 for receiving a snap ring 138, which functions tosecure the second toggle 32 to the housing member 20.

By way of example only, the gear 124 has a generally circularcross-section and includes a central lumen 125 extending therethroughand a plurality of teeth 140 in the form of vertical ridges distributedabout the perimeter of the gear 124. The central lumen 125 includes aplanar surface 127 configured to mate with the planar surface 134 of theactuator 122 to transfer the torque applied by a user to the handleportion 128 to the gear 124, thus turning the gear 124. The teeth 140 ofthe gear 124 are configured to mate with the teeth 114 of the medialrack member 108. As shown by way of example in FIG. 15, the secondtoggle 32 is positioned adjacent the medial rack member 108. As thehandle portion 128 of the actuator 122 is turned by a user, the gear 124causes the medial rack 108 to translate in a medial (or lateral)direction. For example, when the handle portion 128 is rotated in aclockwise direction, the medial rack 128 will move in a medial direction(i.e. toward the spinal column, assuming proper placement of theretractor relative to the spine). The effect of this movement is thatthe medial retractor blade 18, through its connection to the medial rack108 will move in a medial direction, thereby retracting soft tissue andexpanding the operative corridor. The medial rack 108 thus contributesto the customizable nature of the operative corridor.

The release member 126 includes body 142, a tab 144, and a flange 146.The body 142 is a generally circular member having a central lumen 148extending therethrough. The central lumen 148 is dimensioned to receivethe post 132 of the actuator 122. The tab 144 extends radially from thebody and functions as a manipulation point for the user. The flange 146includes a ratchet member 150 that is dimensioned to interact with theteeth 114 of the medial rack member 108. The release member 126 furtherincludes a spring 152 positioned between the tab 144 and the housing 20that biases the ratchet member 150 into an engaged position relative tothe teeth 114. Thus, as the gear 124 turns and the medial member 108moves, the ratchet member 150 clicks into engagement with each passingtooth 114. Thus the ratchet member 150 provides for controlledtranslation of the medial rack member 108, and creating a customizableoperative corridor established in incremental amounts. The ratchetmember 150 further prevents unwanted migration of the medial rack member108 such that the desired operative corridor will not alter onceestablished. The ratchet member 150 is configured to allow forunidirectional movement of the medial rack member 108 relative theretowhile the ratchet member 150 is engaged to the gear 124. The ratchetmember 150 effectively prevents counterclockwise turning of the handlemember 128. To contract the operative corridor, for example uponcompletion of the desired surgical procedure, the user activates the tab144, causing the ratchet member 108 to disengage from the teeth 114.This allows for free translation of the medial rack member 108 relativeto the housing member 20. That is, a counterclockwise turning of thehandle member 128 with the ratchet member 150 disengaged will cause themedial rack member 108 to translate in an opposite direction (e.g.lateral direction, away from the spine.

FIGS. 18-19 illustrate the first arm member 26 in greater detail. Thefirst arm member 26 includes a front body portion 160, a rear bodyportion 162, a first flange 164, and a second flange 166. The front bodyportion includes a front surface 168 and a top surface 170. The frontsurface 168 includes an aperture 172 formed therein and extending intothe front body portion 160. The aperture 172 is dimensioned to receivethe engagement post 230 of the first retractor blade 14 (FIG. 6) toenable engagement of the first retractor blade 14 to the retractor body12. The top surface 170 includes a second aperture 174 configured toreceive a set screw 176 (FIG. 7). The set screw 176 functions to lockthe engagement post 230 within the aperture 172, preventing unwantedejection of the first retractor blade 14 from the first arm member 26.The rear body portion includes a lower-facing inside tapered surface 178that allows the medial blade 18 to pivot within a plane that istransverse to the longitudinal axis of the medial rack member 108. Thispivoting enables intraoperative repositioning of the retractor body 12relative to the surgical target site without the need to detach theretractor body 12 from the articulating arm. The net effect is to alterthe approach angle of the operative corridor relative to the surgicaltarget site.

The first flange 164 extends axially from the rear body portion 162 andincludes a third aperture 180 and fourth aperture 182. The thirdaperture 180 is configured to securely mate with the first end 62 of thefirst rack member 58 such that the first arm member 26 moves with thefirst rack member 58. By way of example only, the first arm member 26can be securely mated with the first rack member 58 by welding,adhesive, snap-fit, friction-fit, or any other suitable method.Alternatively, the first arm member 26 can be integrally formed with thefirst rack member 58 without departing from the scope of the presentinvention. The fourth aperture 182 is configured to allow passage of thesecond rack member 60 therethrough. The third and fourth apertures 180,182 are generally rectangular in shape, however other shapes arepossible depending on the cross-sectional shapes of the first and secondrack members 58, 60. The second flange 166 extends axially from thefront body portion 160 and includes a generally planar upper surface 184and a curved medial surface 186. The second flange 166 interacts withthe thumbscrew 240 of the first retractor blade 14 and functions as ashelf to enable the lockable adjusted angulation feature of the firstretractor blade 14, as well as an alternative distraction feature of thetissue retraction system 10, each of which will be described in greaterdetail below.

FIGS. 20-21 illustrate the second arm member 28 in greater detail. Thesecond arm member 28 includes a front body portion 190, a rear bodyportion 192, a first flange 194, and a second flange 196. The front bodyportion includes a front surface 198 and a top surface 200. The frontsurface 198 includes an aperture 202 formed therein and extending intothe front body portion 190. The aperture 202 is dimensioned to receivethe engagement post 230 of the second retractor blade 16 (FIG. 6) toenable engagement of the second retractor blade 16 to the retractor body12. The top surface 200 includes a second aperture 204 configured toreceive a set screw 206 (FIG. 7). The set screw 206 functions to lockthe engagement post 230 within the aperture 202, preventing unwantedejection of the second retractor blade 16 from the first arm member 28.The rear body portion includes a lower-facing inside tapered surface 208that that allows the medial blade 18 to pivot within a plane that istransverse to the longitudinal axis of the medial rack member 108. Thispivoting enables intraoperative repositioning of the retractor body 12relative to the surgical target site without the need to detach theretractor body 12 from the articulating arm. The net effect is to alterthe approach angle of the operative corridor relative to the surgicaltarget site.

The first flange 194 extends axially from the rear body portion 192 andincludes a third aperture 210. The third aperture 210 is configured tosecurely mate with the first end 70 of the second rack member 60 suchthat the second arm member 28 moves with the second rack member 60. Byway of example only, the second arm member 28 can be securely mated withthe second rack member 60 by welding, adhesive, snap-fit, friction-fit,or any other suitable method. Alternatively, the second arm member 28can be integrally formed with the second rack member 60 withoutdeparting from the scope of the present invention. The third aperture210 is generally rectangular in shape, however other shapes are possibledepending on the cross-sectional shapes of the second rack member 60.The second flange 196 extends axially from the front body portion 190and includes a generally planar upper surface 214 and a curved medialsurface 216. The second flange 196 interacts with the thumbscrew 240 ofthe second retractor blade 16 and functions as a shelf to enable thelockable adjusted angulation feature of the second retractor blade 16,as well as an alternative distraction feature of the tissue retractionsystem 10, each of which will be described in greater detail below.

The retractor blades 14, 16 may be provided in any size or shapesuitable to establish and maintain an operative corridor to the surgicaltarget site. In one embodiment, the retractor blades 14, 16 can beindividually selected for appropriate length. Therefore, the retractorblades 14, 16 can be of different lengths which gives the surgeonadditional control over the shape and size of the operative corridor (asshown for example in FIGS. 62 and 63). The retractor blades 14, 16 maybe provided having a generally arcuate cross-section to facilitate acircular or generally oblong surgical corridor. FIGS. 22-25 illustratean example of a first retractor blade 14 according to the presentinvention. FIG. 26 is an exploded view of the first retractor blade 14.For the purposes of illustration, the specific features of the inventionwill be described in relation to the first retractor blade 14. Howeverit should be understood that the features described in relation to firstretractor blade 14 are the same for second retractor blade 16, butprovided in a mirror-image configuration. Thus, though the first andsecond retractor blades 14 and 16 are not strictly interchangeable, thefeatures of each blade are virtually identical rendering a repeatdiscussion unnecessary as cumulative.

Referring now to FIGS. 22-26, the first retractor blade 14 includes anattachment portion 220 and a blade portion 222 extending distally fromthe attachment portion 220. The attachment portion 220 has a front side224, a back side 226, and a top surface 227. The back side 226 includesa first aperture 228 extending into the upper attachment portion 220 andconfigured to receive an engagement post 230 therein. The engagementpost 230 is configured to mate with the aperture 172 of the first armmember 26 to couple the first retractor blade 14 with the retractor body12. Correspondingly, the engagement post 230 is configured to mate withthe aperture 202 of the second arm member 28 to couple the secondretractor blade 16 with the retractor body 12. The attachment portion220 further includes a pair of second apertures 232 extending throughthe attachment portion 220 parallel to one another and transverse to thefirst aperture 228. The second apertures 232 are vertically offset fromthe first aperture 228 but are at least partially in communication withthe first aperture 228. The second apertures 232 are configured toreceive pins 234 that operate to secure the engagement post 230 to theretractor blade 14 (explained in further detail below). The attachmentportion further includes a flange 236 extending angularly (relative tothe top surface 227) therefrom, the flange 236 including an aperture 238configured to receive a thumb screw 240 therein. The flange 236 andthumb screw 240 interact with the second flange 166 of the first armmember 26 to enable the lockable angulation feature of the firstretractor blade 14, as well as an alternate tissue distraction featureof the tissue retraction system 10, as will be described in greaterdetail below. By way of example only, both the thumb screw 240 andaperture 238 include threads to enable a threaded engagementtherebetween. However, other engagements are possible without departingfrom the scope of the present invention. By way of example only, theflange 236 is angularly offset from the top surface 227 within a rangeof 15 to 50 degrees, with the preferable angle being approximately 30degrees. The thumbscrew 240 includes a head 241, a shaft 243, and adistal tip 245. The head 241 is generally cylindrical in shape andincludes a rotation feature that enables the user to rotate the thumbscrew 240. The rotation feature may be anything that is suitable toenable rotation of the thumb screw 240, for example including but notlimited to a socket 247 for receiving a driver as shown in FIGS. 22, 23and 26, and/or an external planar surfaces 249 to provide gripping for adriver or a user's hand, as shown in FIGS. 24 and 25.

The blade portion 222 extends distally from the attachment portion 220and includes an outside surface 242, an inside surface 244, a first lip246, and a second lip 248. The outside surface is a smooth arcuatesurface configured to interact with the patient's soft tissue near theoperative corridor. As best seen in FIG. 24, the outside surface 242extends from the attachment portion 220 at a non-orthogonal anglerelative to the top surface 227. Since much of the blade has a generallyuniform thickness, the inside surface 244 extends from the attachmentportion 220 at the same non-orthogonal angle relative to the top surface227. Thus, the effect is that the operative corridor is immediatelyestablished having a conical shape with no further adjustment of thetissue retraction assembly 10 required. Additionally, the blade portion222 extends from the attachment portion 220 such that the blade face(i.e. inner surface 244) is oriented orthogonal to the attachmentportion 220. Thus, when the retractor blade is attached to the retractorbody 10, the inside surface faces 244 the operative corridor at an anglerather than facing directly at the opposing blade, for example between20 and 60 degrees). This orientation of the blade portion relative tothe attachment portion helps optimize the shape (e.g. triangular) of theoperative corridor. The inside surface 244 includes a plurality ofnotches or recesses 250 arranged in a linear alignment thereon, thenotches or recesses 250 being configured to interact with the knob 498of the inserter 400, as will be described in further detail below. Theblade portion 222 further includes a pair of track grooves 252 spacedapart from one another and extending the length of the inside surface244. The track grooves 252 are configured to slideably receive a shimattachment, for example the hoop shim 6 shown and described herein. Itshould be understood, however, that any suitable shim attachment may beused without departing from the scope of the present invention. At thedistal end of each of the track grooves 252 there is a stop 254, whichinteracts with the hoop shim 6 to prevent the hoop shim 6 from passingthe stop 254 once it has been fully engaged to the retractor blade. Thefirst lip 246 and second lip 248 comprise edges of the blade portion 222and each extend along the length of the blade portion 222 from theattachment portion 222 to the distal end of the blade portion 222.Notably, the first and second lips 246, 248 are asymmetric relative toone another. For example, the first lip 246 has a concave portion 256that allows for clearance of spinal anatomy during blade angulation.

Referring to FIG. 26, the engagement post 230 includes a boss 258 and apost 260. The boss 258 is generally cylindrical in shape and isdimensioned to be received within the aperture 172 of the first armmember 26 to couple the first retractor blade 14 with the retractor body12. The boss 258 includes a recess 262 formed therein, the recess 262configured to receive at least a portion of the set screw 176 tosecurely engage the first retractor blade 14 to the retractor body 12.The post 260 extends axially from the boss 258 and is configured to bereceived within aperture 228 of the first retractor blade 14. The post260 further includes a recess 264 formed therein, the recess 264 beingsized and dimensioned to receive at least a portion of both pins 234therein. The pins 234 extend transversely relative to the post 260, andprevent undesirable uncoupling of the post 230 from the first retractorblade 14. In practice, the retractor blade 14 (and retractor blade 16)is provided with the post 230 already secured within the aperture 228with the pins 234 in place. The pins 234 may be secured by any suitablemethod, including for example welding, that ensures that the pins 234securely retain the post 230 within the aperture 238. Although describedherein as using a set screw 176 to secure the first retractor blade 14(and/or second retractor blade 16) to the retractor body 12, anysuitable attachment mechanism can be used without departing from thescope of the present invention. For example, a quick connectionmechanism such as a snap fit engagement is possible, as is a frictionengagement or an integral blade.

Referring to FIGS. 27-30, the medial retractor blade 18 may be providedin any size or shape suitable to establish and maintain an operativecorridor to the surgical target site. By way of example only, the medialretractor blade 18 includes an attachment portion 270 and a bladeportion 272. The attachment portion 270 includes a knob 274 and anaperture 276. The knob 274 is configured to allow manipulation by auser, for example to change the angulation of the medial retractor blade18. The knob also connects to a manual insertion tool (not shown). Byway of example, the manual insertion tool includes a cylinder with acanted coil received in a notch therein. In a natural position, the coilextends into the cylinder. The tapered end of the knob 274 deflects thecanted coil as the knob passes. When the coil reaches the groove formedin the knob, the coil returns to the natural position and secures theblade to the manual inserter. The aperture 276 extends into theattachment portion 270 and is configured to receive the post 116 of themedial retraction member 24 therein to securely attach the medialretractor blade 18 to the retractor body 12. The engagement between themedial retractor blade 18 and the post 116 is provided by way of exampleas a snap-fit engagement allowing for relative easy insertion and/orremoval of the medial retractor blade 18. However, other engagements arepossible without departing from the scope of the present invention,including but not limited to using a set screw (e.g. through the knob274 into the aperture 276), friction engagement, or providing a medialretraction member with integral blade. This engagement allows a user tointraoperatively change the medial retractor blade 18, for example toswap out a shorter blade for a longer blade, and vice versa.

The blade portion 272 includes an upper portion 280 and a lower portion282. The upper portion 280 is adjacent to the attachment portion 270 andextends generally orthogonally therefrom. The lower portion 282 islocated distally of the upper portion 280 and is offset from the upperportion 280 such that it forms an obtuse angle with the upper portion280 (best shown in FIG. 30). By way of example only, the offset is suchthat the distal end of the lower portion 282 is offset from the plane ofthe upper portion 280 by approximately one-quarter of an inch. Dependingupon the length of the blade portion 272, the angle formed between theupper and lower portions 280, 282 is variable to achieve thisone-quarter inch offset. The lower portion 282 is wider than the upperportion to accommodate the retraction of a greater amount of thepatient's soft tissue near the surgical target site. The lower portion282 includes a recess 284 configured to receive a blade extension 290therein. The recess 284 includes an elongated central slot 286 formedtherein and configured to receive a guide extension 292 therein. Therecess 284 may further include a pair of elongated lateral slot 288formed therein on either side of the central aperture 286.

A blade extension 290 may be provided to enhance the functionality ofthe medial retractor blade 18. The blade extension 290 is receivedwithin the recess 284 and is coupled to the medial blade 18 by thefastener 292. According to one embodiment, the blade extension 290 isslideably coupled to the medial blade 18. To enable this slidablecoupling, the fastener 292 is slideably received within the elongatedcentral aperture 286. The blade extension 290 includes a front surface294 and a back surface 296. In use, the blade extension 290 is orientedsuch that the front surface 294 faces the operative corridor, and theback surface 296 engages the patient's soft tissue. The blade extension290 may be generally curved such that the front surface 294 has aconcave curvature and the back surface 296 has a convex curvature or itmay the front and back may be generally flat. The blade extension 290further includes a distal anchor element 298 provided thereon. Thedistal anchor element 298 comprises a roughened surface including aseries of ridges and spike members that enable the clearing away of softtissue from the surgical target site. The distal anchor element 298 hastwo aspects of curvature. The first aspect of curvature is that thedistal anchor element 298 curves toward the back surface 296. The secondaspect of curvature is that the front surface 294 maintains its concavecurvature.

The result is that the distal anchor element 298 acts much the same wayas a “boat anchor” in that it is capable of travelling along thesurgical target site, displacing soft tissue until the distal anchorelement 298 engages hard tissue such as bone. By way of example only,when used during a TLIF procedure such as the one described herein byexample, the distal anchor element 298 advantageously removes softtissue from the facet as it is being retracted, saving the surgeon fromhaving to manually clean the facet. Due to its unique shape, the distalengagement element 298 will either penetrate the bone or become wedgedunderneath the bone. The blade extension 290 is slideably coupled to themedial blade 18 such that, upon tilting or other movement of thesurgical retraction system 10, the blade extension 290 will remainstationary relative to the bone segment while the medial retractor blade18 moves relative to the blade extension 290. The blade extension 290 istherefore capable of telescoping (i.e. extending or retracting) toconform to anatomy during retraction, both with and/or without manualadjustments from the surgeon. Thus, the blade elongates since it issecured distally at the bone and proximally at the retractor body 12. Inthis manner, the surgeon is able to further optimize, customize, andalter the operative corridor without having to disengage the retractorand/or any blades, while ensuring the exposure at the surgical targetsite (the base of the operative corridor) does not change, and therebypreventing previously retracted soft tissue from entering the operativecorridor under the blade. Optionally, the blade extension 290 may bemechanically biased toward the extended position in order to ensure thatits tissue clearing functionality is maximized. This may beaccomplished, for example, by including a spring member (not shown)attached to the medial blade 18 and configured to bias the bladeextension 290 in the distal direction.

FIGS. 31-34 illustrate an example of a hoop shim assembly 6 according toone embodiment of the present invention. The hoop shim assembly 6includes a hoop portion 300 slideably engaged with a shim portion 302.The hoop portion 300 includes a hoop member 304, a first flange 306 anda second flange 308 extending proximally from the hoop member 304. Thehoop member 304 is a generally circular member having a central aperture310 configured to receive a bone anchor 7 therein. The hoop member 304has a first, unlocked position having a first diameter allowing passageof the bone anchor 7 therethrough. In this first position, the head ofthe bone anchor 7 may pass through, but with resistance. The hoop member304 further has a second, locked position, having a second diameter thatdoes not allow passage of the head of the bone anchor 7 therethrough.Thus, when the hoop member 304 is in the locked position, the boneanchor 7 is secured to the hoop shim 6. As will be explained below, thissecured engagement does not mean that the bone anchor 7 isimmobilized—on the contrary it is a polyaxial engagement (as illustratedin FIGS. 58-61). The hoop member 304 may be optionally provided with aninsert 312 (FIGS. 35-37) to provide protective interaction with the boneanchor 7. More specifically, the insert 312 protects the neck of thebone anchor 7 from a metal-on-metal contact with the hoop shim 6, whichcould ultimately weaken the bone anchor 7. The insert 312 may becomposed of any suitable materials, including but not limited topolyetheretherketone (PEEK).

The first flange 306 is generally elongated and extends generallyperpendicularly in a proximal direction from the hoop member 304. Thefirst flange has a wing 314 extending at least partially along thelength of the flange 306 from the proximal end toward the distal end.The wing 314 is dimensioned to engage one of the track grooves 252 ofthe first retractor blade 14 (and/or second retractor blade 16) toenable slidable engagement of the hoop shim assembly 6 with theretractor blade 14 (as shown in FIG. 38, for example). The first flange306 further includes a tab member 316 projecting in a forward direction(i.e. same direction as the hoop member 304). The tab member 316 isgenerally rectangular and configured to slidably engage the verticalslot 338 of the shim portion 302. The tab member 316 has a generallyU-shaped retaining pin 318 attached thereto that prevents the tab member316 from becoming disengaged with the vertical slot 338 during use. Byway of example only, the retaining pin 318 is welded to the tab member316 during assembly of the hoop shim assembly 6, however otherattachment methods are possible without departing from the scope of thepresent invention. For example, the tab member 316 and retaining pin 318may be integrally formed with one another and then welded onto the firstflange 306. Additionally, a retaining plate may be welded over the tabinstead of the retaining pin.

The second flange 308 is generally elongated and extends generallyperpendicularly in a proximal direction from the hoop member 304opposite and generally parallel (in an initial position) to the firstflange 306. The second flange 306 has a distal portion 320, a proximalportion 322, and an intermediate portion 324 positioned between thedistal portion 320 and proximal portion 322. The distal portion 320 isattached to the hoop member 304, and has a first width. The proximalportion 322 has a second width that enables the proximal portion 322 topass the knob 346 of the shim portion 302 and into the recess 344 of theshim portion 302. By way of example only, the first width is greaterthan the second width. The intermediate portion 324 has a third widththat is greater than both the first and second widths, and a convex edge326 extending from the proximal portion 322 to an apex 328. Theintermediate portion 324 further includes a concave edge 330 extendingbetween the apex 328 and the distal portion 320.

The shim portion 302 is a generally rectangular elongated member havinga proximal end 332 and a distal end 334. The shim portion 302 furtherincludes a first wing 336 extending substantially the length of one sideof the shim portion 302 (e.g. the side that corresponds to the secondflange 308 of the hoop portion 300). The first wing 336 is dimensionedto engage one of the track groove 252 of the first retractor blade 14(and/or second retractor blade 16) to enable slidable engagement of thehoop shim assembly 6 with the retractor blade 14 (as shown in FIG. 36,for example). The shim portion further includes an elongated verticalslot 338 extending substantially the length of the shim portion 302. Thevertical slot 338 is configured to slidably receive the tab member 316therein. The shim portion 302 further includes a horizontal slot 340positioned near the proximal end 332. The horizontal slot 340 isdimensioned to engage the distal projection 366 of the hoop shim removaltool 350, as described below. The horizontal slot has a ramped surface341 extending toward the proximal end 332 of the shim portion 302. Byway of example only, the vertical slot 338 and horizontal slot 340 areshown as one connected L-shaped aperture, however separate apertures arepossible without departing from the scope of the invention. The shimportion 302 further includes a second wing 342 positioned near theproximal end 332 on the opposite side of the shim portion 302 from thefirst wing 336. The second wing 342 is dimensioned to align with thewing 314 of the first flange 306 during use (as shown in FIG. 33). Thesecond wing 342 has the same function as the first wing 336. The shimportion 302 further includes a recess 344 formed within the back side ofthe shim portion. The recess 344 is dimensioned to receive at least aportion of the second flange 308 of the hoop portion 300, to enable thehoop shim 6 to transition to a locked position. The recess 344 alsoincludes a knob 346 positioned at the distal end of the recess 344. Theknob 346 functions to reduce the width of the opening of the recess 344to prevent easy disengagement of the hoop portion 300.

In use, the hoop shim assembly 6 is preferably provided in apreassembled form in which the tab member 316 is engaged within thevertical slot 338 and the retaining pin 318 is welded to the tab member316, preventing disengagement of the tab member 316 from the verticalslot 338. In the initial position, the proximal portion 322 of thesecond flange 308 is positioned within the recess 344 of the shimportion 302 and adjacent to the knob 346. In this initial position, abone anchor 7 may be loosely engaged to the hoop member 304, within thecentral aperture 310. To secure the bone anchor 7 to the hoop shimassembly 6, the hoop shim assembly 6 is moved from its initial unlockedposition to a final locked position. To achieve this, the first andsecond flanges 306, 308 are slidably advanced proximally along the shimportion 302. The convex edge 326 of the intermediate portion 324 of thesecond flange 308 includes a relatively gradual curvature. As the secondflange 308 is advanced past the knob 346 and into the recess 344, theinteraction between the knob 346 and the convex edge 326 causes thesecond flange 308 to deflect toward the first flange 306. The width ofthe intermediate portion is preferably such that the intermediateportion still engages the inner wall of the recess and remains in thedeflected position. The concave edge 330 has a relatively steep concavecurvature, and thus the apex 328 will not reverse past the knob 346absent sufficient applied force. Once the apex 328 is beyond the knob346 and within the recess 344 of the shim portion 302, the hoop shimassembly 6 is in a locked position, and the bone anchor 7 issuccessfully and securely engaged thereto (e.g. FIG. 44).

This final, locked position is illustrated by way of example only inFIGS. 35-37. The bone anchor 7 is positioned within the aperture 310 ofthe hoop portion 300. An insert 312 is provided within the hoop member304. Notably, the head 8 of the bone anchor 7 is positioned proximallyof the hoop member 304, and in this position is unable to pass throughthe aperture. The threaded shank 9 of the bone anchor 7 extends distallyof the hoop member 304.

FIG. 38 illustrates a hoop shim assembly 6 engaged with a retractorblade 14, in an unlocked position and without a bone anchor engagedthereto. FIG. 39 illustrates a hoop shim assembly 6 lockingly engaged toa bone anchor 7 and engaged with a retractor blade 14. The hoop shimassembly 6 may be coupled with the bone anchor 7 and/or retractor blade14/16 either before or during a surgical procedure. In one embodiment,the hoop shim assembly 6, bone anchor 7, and retractor blade 14 areprovided in a pre-assembled state. In such an embodiment, the hoop shimassembly 6 is first coupled to a retractor blade 14 as described above,in an unlocked position. A bone anchor 7 is then introduced such thatthe neck region is within the central aperture 310. At this point theengagement between the hoop shim assembly 6 and bone anchor 7 isunsecure. The hoop shim assembly 6 is then moved into a locked position,securing the bone anchor 7 therein. The bone anchor 7, hoop shimassembly 6, and retractor blade 14 may then be coupled to an inserter,for example such as the inserter 400 shown and described in relation toFIGS. 64-78 below, and advanced simultaneously through the operativecorridor to the surgical target site. Alternatively, the bone anchor 7may be placed within the surgical target site and then engaged with thehoop shim assemblies 6 by slipping the heads 8 of the bone anchors 7within the central aperture 310 of the hoop shim assembly 6 and thenlocking the hoop shim assemblies 6. Moreover, the hoop shim assembly 6may be intraoperatively engaged and/or disengaged from an implanted boneanchor 7 within a surgical target site. This feature is advantageous inthat it allows the operative corridor to be registered to an anatomicallandmark, and also removed from that registration, for example if theuser wanted to expand the operative corridor beyond the implanted boneanchors. A further advantage of this feature is that it allows forintraoperative exchange of retractor blades 14, 16, for example to swapout for a longer or shorter blade, without losing the ability toregister the operative corridor to an anatomical landmark, and withoutchanging the position of the retractor body 12.

FIGS. 40-42 illustrate an example of a hoop shim removal tool 350according to one embodiment of the present invention. The hoop shimremoval tool 350 is a generally elongated instrument having a distalengagement member 352, an intermediate shaft 354, and a proximal slaphammer 356 attached thereto. The distal engagement member 352 includes atop panel 358, a bottom panel 360, and a base 362 positioned between thetop and bottom panels 358, 360 at the proximal end of the distalengagement member 352. The top panel 358 has a distal portion 364 thatextends beyond the end of the bottom panel 360. The distal portion 364includes a projection 366 configured to engage the horizontal slot 340of the hoop shim assembly 6. As illustrated in FIG. 42, the projection366 is oriented such that there is an acute angle formed between theprojection 366 and the top panel 358. The projection 366 furtherincludes a ramped leading surface 367 configured to deflect off the shimportion 302 as the distal engagement member 352 is advanced intoengagement with the shim portion 302. The bottom panel 360 includes apair of lateral wings 363 positioned on either side of the bottom panel360. The lateral wings 363 are dimensioned to engage the track grooves252 of the first retractor blade 14 (and/or second retractor blade 16)to enable slidable engagement of the hoop shim removal tool 350 with theretractor blade 14 (as shown in FIG. 43, for example).

The slap hammer 356 includes a distal stop 368, a proximal stop 370, anelongated shaft 372 extending between the distal and proximal stops 368,370, and a slapper 374 slidably positioned on the elongated shaft 372.The slapper 374 is configured to slide along the elongated shaft 372between the distal and proximal stops 368, 370. The slap hammer 356 isdesigned to allow a user to generate a tremendous force in the proximalor distal direction. For example, a user would grab the slapper 374 andexert a force in a proximal direction by “slapping” it against theproximal stop 370.

FIGS. 43-46 illustrate the steps of using the hoop shim removal tool 350to remove the hoop shim 6. First, as illustrated in FIGS. 43-44, thehoop shim removal tool 350 is slidably engaged to the retractor blade 14as described above. The distal engagement member 352 is advanced alongthe retractor blade 14 until the projection 366 engages the locked hoopshim assembly 6. As the projection 366 is being advanced over the shimportion 302 between the proximal end 332 and the horizontal slot 340,the top panel 358 is outwardly displaced. As the projection 366 engagesthe horizontal slot 340, the top panel 358 snaps back into place and asecure engagement is achieved between the hoop shim removal tool 350 andthe hoop shim assembly 6, as illustrated in FIGS. 44 and 45. The userthen slaps the slapper 374 against the proximal stop 370 to generate aproximal force on the shim portion 302 of the hoop shim assembly 6. Thisforce should be great enough to at least pull the knob 346 past theintermediate portion 324 of the second flange 306, causing the hoop shimassembly 6 to return to its unlocked position. In the unlocked position,the aperture 310 has an increased diameter. Another slapping of theslapper 374 should supply enough force to pull the hoop member 304 pastthe head 8 of the anchor member 7, thus disengaging the hoop shim 6 fromthe anchor member 7 (as shown in FIG. 46) and retrieving the hoop shimassembly 6 from the retractor blade track. Of course, a single slappingof the slapper 374 may be sufficient to both unlock the hoop shimassembly 6 and disengage the hoop member 304 from the anchor head 7. Theretractor blade 14 is no longer registered to the anchor member in thesurgical fixation site, but can rather move freely and/or be removedentirely.

Although the hoop shim removal tool 350 has been described by way ofexample with regard to a specific embodiment, other mechanisms arepossible. For example, the slap hammer may be replaced by aKerrision-style trigger without departing from the scope of the presentinvention.

The surgical retraction system 10 described herein may be used in avariety of different surgical techniques involving a variety of areas ofthe body. By way of example only, the surgical retraction system 10 isideal for performing a novel procedure for performing a transforaminallumbar interbody fusion (TLIF) procedure on a human spine. For thepurposes of illustration, the example technique will be explained withregard to a one-level TLIF, in which two adjacent vertebrae are fusedacross a single intervertebral space. However, it should be noted thatthe system and method disclosed herein may be suitable to be used onmultiple vertebral levels without departing from the scope of thepresent invention. Moreover, the system and methods described herein maybe used and/or adapted for use in a variety of different surgicaltechniques involving a variety of areas of the body without departingfrom the scope of the present invention.

Prior to performing this technique, the patient is positioned in theprone position, (i.e. on his/her stomach). The first step in the methodis to locate the pedicles that will in part define the surgical targetsite. The next step is to create an incision in the patient's skin abovethe surgical target site (in this example, an intervertebral disc spacebetween two adjacent vertebrae). Specifically, the incision should bemade between the pedicles along the lateral border. K-wires are thenplaced via a jamshidi through the small incisions into the pedicles onadjacent vertebrae. To assist with this, the surgeon may use a navigatedguidance system, for example one shown and described in commonly ownedPCT Application Nos. PCT/US07/11962, entitled “Surgical TrajectoryMonitoring System and Related Methods,” filed May 17, 2007, andPCT/US08/12121, entitled “Surgical Trajectory Monitoring System andRelated Methods,” filed on Oct. 24, 2008, the entire contents of whichare each incorporated by reference into this disclosure as if set forthfully herein. Once the K-wires are positioned properly within the targetpedicles, the surgeon may create an initial surgical corridor throughfinger dissection. The distance from the vertebral body and surface ofthe skin is measured using a ruled dilator or another suitableinstrument. Another tool may be used to measure the appropriate screwlength by indicating how far into bone the K-wire has been advanced. Thenext step in the procedure is pilot hole formation. Navigated guidanceand fluoroscopic imaging may continue to be used to help the surgeonensure the proper approach and trajectory into the pedicles is beingmaintained. A cannulated tap is then passed over each of the K-wires totap an appropriate sized pilot hole into each of the pedicles.Optionally, the cannulated tap may be substantially insulated andprovided with an electrified tip, or alternatively a second insulatedcannula may be provided while the tap is electrified, in order to enablepedicle integrity testing during pilot hole formation. This function issimilar to the procedure shown and described in U.S. patent applicationSer. No. 10/836,105, now issued as U.S. Pat. No. 7,664,544, filed Apr.30, 2004, entitled “System and Methods for Performing PercutaneousPedicle Integrity Assessments,” the complete disclosure of which ishereby incorporated by reference into this document as if set forthfully herein. Once this is completed, the appropriate length ofretractor blades 14, 16 is selected and assembled with the hoop shimassembly 6, an anchor member 7, and inserter 400 as shown and describedherein. This step is repeated for both the first and second retractorblades 14, 16.

Once the blade-shim-anchor assembly has been securely created, theanchor member 7 (with hoop shim 6 and first retractor blade 14 securelyattached) is advanced through the initial operative corridor and driveninto the pilot hole in a first of the adjacent pedicles. This process isrepeated with the second retractor blade 16 assembly and the secondpilot hole, until the first and second retractor blades 14, 16 areprotruding from the initial incision, with the distal ends of the bladesbeing securely registered to the anchor members 7 via the hoop shimassemblies 6. At this point, the first and second retractor blades 14,16 may be attached to the retractor body 14 as described above. Thesurgeon may then operate the retractor body 12 to cause the retractorblades 14, 16 to move in cranial and caudal directions, respectively, atthe skin level. Because the distal portions of the retractor blades 14,16 are securely (and polyaxially) registered to the implanted anchormembers 7, the anchor members 7 will not move. However, the angle of theretractor blades 14, 16 relative to the anchor members 7 may be adjustedto a desired angle (for example as shown in FIG. 54, and the operativecorridor will be established. Once established, the retractor body 12may be locked to an articulating arm (not shown) by either one of theattachment members 53 of the retractor body 12, or attachment members109 of the medial rack 108. Using a suitable tool or a finger, thesurgeon then releases soft tissue from the facet. A medial retractorblade 16 may then be inserted and retracted as desired and as describedabove. As mentioned previously, the medial retractor blade may operateto clear remaining soft tissue from the facet. The medial retractorblade 16 may be angled to match the operative corridor by pivoting theblade in a plane that is transverse to the longitudinal axis of themedial rack 108. In this fashion, the entire operative corridor may beestablished at an angle that is suitable for superior access to the discspace.

At this point, the tissue retraction assembly 10 is positioned as shownby way of example in FIGS. 47-50. The surgeon has established a primaryoperative corridor 4 to a surgical target site 1, and has distinctlandmarks (i.e. the implanted anchor members 7) delineating the cranialand caudal boundaries of the relevant operative window (the respectivepedicles of the superior and inferior vertebrae 2, 3). The surgeon cannow perform the necessary steps to clean out the intervertebral discspace and perform the interbody fusion procedure. This example procedurecontinues with a facetectomy in which at least a portion of the facetjoint is removed, allowing access to the intervertebral disc space. Thedisc space is prepared using techniques generally known in the art,including disc brushes, scrapers, etc. The interbody implant is theninserted into the cleaned out disc space. By way of example only thismay include, but not be limited to, inserting one or more artificial orallograft implants within the intervertebral space. According to oneexample, the implant may be inserted and positioned obliquely across thedisc space. If necessary, the surgeon may use the tissue retractionsystem 10 to distract the disc space without expanding the incision atthe patient's skin and without any further instrumentation. This tissuedistraction feature of the disclosed device is described in greaterdetail below.

After placement of the interbody implant, the distraction of the screwsis released, and the hoop shim assemblies 6 are removed using the hoopshim removal tool 350 as described above. The surgeon then “opens” theretractor slightly in a caudal-cranial direction using the thumbscrews240 on the blades (opposed to the rack assembly 22) as described belowto increase the space around the pedicle screws. The pedicle screwtulips are then inserted onto the pedicle screws (FIG. 51). A posteriorfixation rod is then placed within the tulips (FIG. 52), followed bycompression (if necessary) and locking of the rod. With the procedurecompleted, the retractor can be returned to a “closed” position and thenremoved from the patient, closing the operative corridor (FIG. 53). Thesurgeon will then close the operative wound, completing the procedure.

The surgical fixation system 5 shown and described herein by way ofexample boasts a variety of advantageous features. An advantage of thepresent system is that it allows for intraoperative adjustment of theoperative corridor, and in particular the angle of approach (in alldirections) to the surgical target site with assurance that the exposurewill not stray from the desired target site because the distal ends ofthe retractor blades 14, 16 are fixed in position at the target site.This advantage is accomplished by one or more features of the presentinvention. For example, the retractor blades 14, 16 that define theexposure are fixed to the target site with a polyaxial engagement (e.g.the hoops shim assemblies 6 have a polyaxial interaction with the boneanchors 7). The retractor blades 14, 16, 18 are each capable ofmultiaxial movement relative to the retractor body 12. The first andsecond retractor blades 14, 16 are capable of being locked in anangulated position.

FIGS. 54-57 illustrate extreme angulation capabilities of the tissueretraction system 10. Once the primary operative corridor has beenestablished as described above, it may become necessary to alter theposition of the operative corridor, for example to be able to accessintervertebral disc material that otherwise would not be able to beaccessed. With the tissue retraction system 10 disclosed herein theangle of the operative corridor 4 may be altered without changing thesurgical window at the target site—only the approach angle changes. Thisis enabled by the multiaxial movement capabilities of the retractorblades 14, 16, 18. In this context, “multiaxial” means having theability to pivot in a number of different directions relative to aninitial position along one axis (or in a single plane). For example,each of the retractor blades 14, 16, has the ability to pivot in both acaudal and cranial direction. Similarly, the medial blade 18 has theability to pivot in a caudal and cranial direction. It is contemplatedthat the retractor blades 14, 16, 18 may also be capable of polyaxialmovement. In this context, “polyaxial” means having the ability to pivotin a number of different directions relative to an initial positionalong a number of axes (or in a number of different planes). Thus,blades may also be provided with the ability to pivot in a medial and/orlateral direction, or in a generally arcuate manner without departingfrom the scope of the present invention. Similarly, the medial retractorblade 18 may also be provided with the ability to pivot in a medialand/or lateral direction, or in a generally arcuate manner withoutdeparting from the scope of the present invention.

As mentioned previously, the result of this pivoting is that the tissueretraction system 10 described herein is capable of establishing andmaintaining an angled operative corridor 4 to a surgical target site.The tissue retraction system 10 is able maintain this angulation due tothe thumb screws 240 that are provided on each of the retractor blades14, 16. As described earlier in relation to FIGS. 22-26, the flange 236and thumb screw 240 of the first retractor blade 14 interact with thesecond flange 166 of the first arm member 26 to enable the lockableangulation feature of the first retractor blade 14. Similarly, theflange 236 and thumb screw 240 of the second retractor blade 16 interactwith the second flange 196 of the second arm member 28 to enable thelockable angulation feature of the second retractor blade 16. In oneembodiment, the aperture 238 on the flange 236 and the thumb screw 240are both threaded such that there is a threaded engagement between theflange 236 and thumb screw 240. As best illustrated in FIG. 57, once adesired angulation of the first retractor blade 14 is established, thethumb screw 240 is rotated clockwise to advance the threaded shaft 243through the threaded aperture 238 until the distal tip 245 of the thumbscrew 240 engages the top surface 184 of the second flange 166. At thispoint, the user stops rotating the thumb screw 240 and the firstretractor blade 14 is prevented from pivoting in the opposite directiondue to the threaded engagement of the flange 236 and thumb screw 240, aswell as the engagement between the distal tip 245 of the thumb screw 240and the top surface 184 of the second flange 166. This process isrepeated for the second retractor blade 16. For example, once a desiredangulation of the second retractor blade 16 is established, the thumbscrew 240 is rotated clockwise to advance the threaded shaft 243 throughthe threaded aperture 238 until the distal tip 245 of the thumb screw240 engages the top surface 214 of the second flange 196. At this point,the user stops rotating the thumb screw 240 and the second retractorblade 16 is prevented from pivoting in the opposite direction due to thethreaded engagement of the flange 236 and thumb screw 240, as well asthe engagement between the distal tip 245 of the thumb screw 240 and thetop surface 214 of the second flange 196.

The medial retractor blade 18 may be provided with a locking element orbe allowed to freely pivot. However, once the first and second retractorblades 14, 16 are locked in position, the operative corridor 4 isestablished and will not move whether or not the medial retractor blade18 is locked in position.

FIGS. 58-61 illustrate the polyaxial engagement between the hoop shimassembly 6 and the anchor member 7. Due to the unique structure of thehoop member 304 and the head 8 of the anchor element 7, the hoop shimassembly 6 (and by extension the retractor blade 14/16) is able tomaintain secure engagement to the anchor element 7 at a variety ofangulations, including variable angulations. For example the hoop member304 fits securely but loosely over the head 8 of the anchor member 7 toallow for locking of the hoop shim assembly 6 to the anchor member 7 butalso allowing for polyaxial engagement therewith. This interactionbetween the hoop member 304 and anchor member 7 will serve severalfunctions. First it provides a temporary but secure attachment for theretractor blades 14/16 to help keep the operative corridor secure duringthe surgical procedure and act as fixed anatomical landmarks for thesurgeon, provided the surgeon knows exactly where the bone anchors areplaced. In other words, the operative window at the surgical target sitewill not move even if the position of the retractor body 12 were tomove, or even if the angles of the blades 14/16 were to alter, becausethe blades 14, 16 are registered to the anchor members 7, which arealready implanted in the bone.

Secondly, this interaction provides a pivot point for the retractorassembly, allowing the surgeon to tilt the retractor assembly (andtherefore the operative corridor) while maintaining the proper placementof the distal end of the operative corridor (e.g. the space between theanchor members 7). Another benefit to this feature is that the retractorbody 12 is always securely registered to the patient. Yet anotherbenefit of this feature is that it enables multi-axial maneuverabilityof the retractor blades 14/16. More specifically, each retractor bladeis able to tilt in a caudal direction or cranial direction (or evenmedial or lateral directions) without adversely affecting the engagementbetween the hoop shim assembly 6 and the anchor member 7.

A second advantage of the tissue retraction system 10 disclosed hereinis that it functions not only as a soft tissue retractor but also mayfunction as a distracter capable of moving the adjacent vertebrae apartin order to distract the intervertebral disc space in a caudal-cranialdirection. There are at least two distinct ways in which this can beaccomplished. The first is by locking the retractor blades 14, 16 in adesired orientation as described above and then operating the firsttoggle 30 of the rack member 22 to cause the retractor blades 14, 16 tomove apart from one another, thereby distracting the disc space. Withthis first instance, there would necessarily be an expansion of theoperative wound at the skin level, because the retractor body 12 isworking to expand the entire operative corridor. The general shape ofthe operative corridor (e.g. angulation of the retractor blades 14, 16)remains constant but the width of the operative corridor expands.

The second, alternative method of distracting the disc space involvesmaintaining the first and second rack members 58, 60 in a stationaryposition, and then using the thumb screws 240 on the first and secondretractor blades 14, 16 to cause the distal ends of the retractor blades14, 16 to migrate apart from one another. Since these distal ends areattached to the implanted bone anchors 7, the result is a separation ofthe vertebral bodies. However, since the retractor body 12 remainsconstant, there is no enlargement of the surgical wound at the skinlevel. The general conical shape of the operative corridor itselfchanges, as the angulation of the blades 14, 16 also changes. This typeof distraction can potentially have less detrimental effect to thepatient because the skin incision is relatively unaltered. Referringagain to FIG. 57, in order to accomplish this distraction, the userstarts with the first and second retractor blades 14, 16 locked inposition such that the distal tip 245 of the thumb screw 240 of thefirst retractor blade 14 is engaged with the top surface 184 of thesecond flange 166 of the first retractor arm 26, and the distal tip 245of the thumb screw 240 of the second retractor blade 16 is engaged withthe top surface 214 of the second flange 196 of the second retractor arm28. At this point, the user would rotate one or both of the thumb screws240 in a clockwise direction (to enable increased distraction) or in acounterclockwise direction (to decrease the distraction).

For the sake of simplicity, this process will be further described inrelation to the first retractor blade 14 only, however it will beunderstood that the process is the same for the second retractor blade16 as well. As the user rotates the thumb screw 240 when the distal tip245 is engaged with the top surface 184 of the second flange 166 of thefirst retractor arm 26, flange 236 will effectively travel in a proximaldirection relative to the shaft 243 of the thumb screw 240, since thedistal tip 245 is prevented from travelling in a distal direction by thesecond flange 166. This causes the distal end of the retractor blade toswing outward, or away from the working channel. Since the distal end isengaged to a bone anchor 7 via a hoop shim assembly 6 as describedabove, the movement of the distal end of the retractor blade will causethe bony segment to be displaced in the same direction (away from theworking channel). This causes distraction of the disc space. Thisprocess can be performed independently for each retractor blade 14, 16,thus enabling further customization of the operative corridor and/orsurgical target site.

A third advantage of the tissue retraction system 10 described herein isthe ability to intraoperatively exchange retractor blades 14, 16, 18.For example, this may be useful in situations in which the user desiresone blade to be longer than the other. FIGS. 62-63 illustrate option fordifferent sized blades. Because the blades 14, 16 are independentlyinsertable, and are also inserted prior to the retractor body 12 beingattached, an opportunity exists for a surgeon to elect multiple sizedretractor blades depending upon the type of procedure to be performed.For example, if the surgeon is anticipating the need for extremeangulation in a particular direction, he or she may choose to use alonger retractor blade to accommodate for increased angle of one of theretractor blades. The interchangeability of the retractor blades allowsfor customization of the operative corridor.

FIGS. 64-67 illustrate an example of an inserter 400 for use with thetissue retraction system 10 of the present invention. As mentionedpreviously, the bone anchor 7, hoop shim assembly 6, and retractor blade14 may then be coupled to an inserter, and advanced simultaneouslythrough the operative corridor to the surgical target site. FIGS. 64 and65 illustrate a bone anchor 7, hoop shim assembly 6, and retractor blade14 coupled to the inserter 400. In order to couple the variouscomponents together prior to insertion through an operative corridor,the first step is to slidably engage the unlocked hoop shim assembly 6with the retractor blade 6 as described above. The bone anchor 7 is thenloosely coupled with the hoop shim assembly 6. The hoop shim assembly 6is then locked with the bone anchor 7 engaged. The inserter 400 is thenslidably engaged to the retractor blade 14 (as described below),advanced toward the bone anchor 7, and then releasably coupled to thebone anchor as described below. Once this coupling has occurred, theinsertion assembly is very secure due to the fact that each component(bone anchor 7, hoop shim assembly 6, retractor blade 14 and inserter400) is coupled to two other components at the same time. Specifically,the bone anchor 7 is coupled to the hoop shim assembly 6 and inserter400. The hoop shim assembly 6 is coupled to the bone anchor 7 andretractor blade 14. The retractor blade 400 is coupled to the hoop shimassembly 6 and the inserter 400. The inserter 400 is coupled to the boneanchor 7 and retractor blade 14. The result is a secure and robustengagement that allows the user to safely advance the components to thesurgical target site.

Referring to FIGS. 66 and 67, the inserter 400 includes a receiverassembly 402, a driver assembly 404, and an engagement assembly 406.Broadly, the receiver assembly 402 includes a receiver member 408, anelongated shaft 410, and a thumbwheel 412, and functions to securelyengage the exterior of the head 8 of the anchor member 7. The driverassembly 404 includes cannulated driver 414, a housing 416, and aproximal engagement member 418, and functions to engage the head of thebone anchor 7 and drive it into the bone. The engagement assembly 406includes a blade engagement member 420 and functions to engage theinserter 400 and retractor blade 14, as well as enable the locking ofthe head 8 of the anchor member 7 within the receiver assembly 402.

Referring to FIGS. 68-70, the receiver member 408 is a generallycylindrical member having a proximal end 424, a distal end 426, and abody 428 extending therebetween. The receiver member 408 furtherincludes a central lumen 430 extending therethrough from the proximalend 424 to the distal end 426. At the proximal end 424, the centrallumen 430 has a first diameter. At the distal end 426, the central lumen430 has a second diameter that is greater than the first diameter,forming a receptacle 432 configured to receive the head 8 of the anchormember 7 therein. The distal end 426 further includes a plurality ofdeflectable flanges 434 arranged radially about the distal end 426. Thedeflectable flanges 434 include a raised surface 436 extending radiallyoutward at the exterior of the distal end 426. Within the central lumen430, the deflectable flanges 436 also include a concave surface 438 suchthat the opening 440 of the central lumen 430 has a smaller diameterthan that of the receptacle 432. The raised surfaces 436 interact withthe distal aperture 494 of the engagement assembly 406 to cause theflanges 434 to be deflected inward. This in turn causes the concavesurfaces 438 to engage the neck 9 of the bone anchor 7, therebyentrapping the head 8 within the receptacle 432. The proximal end 424further includes a plurality of apertures 442 formed therein, theapertures configured to receive connectors 452 at the distal end 446 ofthe shaft 410. By way of example only, the receiver member 408 includesfour apertures 442, however, any number may be provided withoutdeparting from the scope of the present invention.

Referring to FIGS. 67, 71 and 72, the shaft 410 has a proximal end 444and a distal end 446. The proximal end 444 includes a threaded region448 configured to threadedly engage the thumbwheel 412, as will bedescribed in further detail below. The shaft 410 is cannulated andtherefore has a lumen 450 extending therethrough from the proximal end444 to the distal end 446. The lumen 450 is dimensioned to receive aK-wire (not shown) or similar guidance tool to guide the inserter 400 tothe surgical target site during a surgical procedure. The distal end 446includes a plurality of connectors 452 dimensioned to be received withinthe apertures 442 on the receiver member 408. The connectors 452 snuglyfit within the apertures 442 and are provided to prevent the receivermember 408 from rotating when the bone anchor 7 is being driven intobone.

The thumbwheel 412 has a lumen 454 extending axially therethrough andincludes a pair of recesses 456 located on either end of the lumen 454the recesses are each configured to receive a stopper 458 therein. Thestoppers 458 are annular members that help hold the thumbwheel 412 inplace and provide friction resistance to the thumbwheel 412 so that someforce is required to turn the thumbwheel 412. The lumen 454 is threadedto interact with the threaded region 448 of the shaft 410. As will beexplained below, the thumbwheel 412 is operable to cause the shaft 410to translate proximally and distally, thereby causing the receivermember 408 to translate in and out of the distal aperture 494 of theengagement assembly 406, and further causing the receiver member 408 tolock or unlock a head of an anchor member 7 therein. The thumbwheel 412is further provided with a suitable friction engagement element 460, forexample ridges, recesses, bumps, adhesives, and the like, for enabling auser to grip and rotate the thumbwheel 412.

Referring to FIGS. 67 and 73, the housing 416 includes a proximal end462, a distal end 464, and an aperture 466 positioned therein. Theaperture 466 is dimensioned to receive the thumbwheel 412 and at least aportion of each of the stoppers 458. The housing 416 is cannulated,having a lumen 468 extending therethrough dimensioned to receive theshaft 410 therein. The proximal end 462 includes a post 470 dimensionedto engage the proximal attachment member 418. The distal end 464includes a second post 472 dimensioned to engage the cannulated driver414. The proximal engagement member 418 extends proximally from thehousing 416 and is configured to engage an attachment (e.g. a T-handle)that enables the application of torque by a user in order to drive abone anchor 7 into bone.

Referring to FIGS. 74 and 75, the cannulated driver 414 includes aproximal end 474, a distal end 476, and an elongated cylindrical shaft478 extending therebetween. The cannulated driver 414 further includes alumen 480 extending axially therethrough, the lumen 480 configured toreceive the shaft 410 of the receiver assembly 402. The distal end 476includes a first cylinder 482 adjacent the shaft 478 and a secondcylinder 484 extending distally from the first cylinder 482. The firstcylinder 482 is configured to engage the blade engagement member 406.The second cylinder 484 has a diameter that is smaller than the diameterof the first cylinder 482, and is configured to be at least partiallyreceived within the lumen 430 of the receiver member 408. The secondcylinder 484 includes a plurality of elongated slots 488 extendingaxially therethrough. The elongated slots 488 are provided in a numbercorresponding to the number of connectors 452 provided on the shaft 410.By way of example, the second cylinder 484 includes four elongated slots488, however any number is possible. The elongated slots 488 each havewidth dimension corresponding to the diameter of the connectors 452. Theconnectors 452 are slidably engaged within the elongated slots 488, asillustrated by way of example in FIGS. 76 and 77. The length of theelongated slots 488 determine the degree of translation of the shaft410, and thus the receiver member 408 that is allowed upon operation ofthe thumbwheel 412.

Referring to FIG. 78, the engagement assembly 406 includes a bladeengagement member 420 and a cylindrical body 422. The blade engagementmember has a pair of elongated wings 490 that are configured to slidablyengage the track grooves 252 of the first and/or second retractor blades14, 16. The cylindrical body 422 includes a lumen 492 extending axiallytherethrough and a distal aperture 494. The lumen 492 is dimensioned toreceive the receiver member 408 and cannulated driver 414 therein. Theaperture 494 is dimensioned to allow passage of the receiver member 408therethrough. The blade engagement member 420 further includes anaxially oriented deflectable flange 496 extending thereon, thedeflectable flange 496 including a knob 498 configured to be receivedwithin the recesses 250 in the retractor blade 14. When the knob 498 ispositioned within a recess (or notch) 250, the flange 496 is in arelaxed position. As the inserter 400 is being advanced along theretractor blade 14, the knob 498 is forced out of the recess 250 and theflange 496 is deflected and under stress. When the knob 498 enters thenext recess 250, the flange 496 snaps back into its initial position.This provides both a tactile and audible indication of the sequentialadvancement of the knob 498 along the series of recesses 250. In thismanner, the user may be able to use the audible and tactile indicationsto determine how far the inserter 400 has been advanced along theretractor blade 14.

In use, preferably the hoop shim assembly 6, bone anchor 7, andretractor blade 14 are coupled together as described above, with thehoop shim assembly 6 in the locked position. The inserter 400 isprovided in an initial position, with the distal end 426 of the receivermember 408 protruding from the distal aperture 494 of the engagementassembly 406. The inserter 400 is coupled to the retractor blade 14 viathe engagement between the wings 490 of the engagement assembly 406 andthe track grooves 252 of the retractor blade 14. Once coupled to theretractor blade 14, the inserter is slidably advanced along theretractor blade until the head 8 of the anchor member 7 is receivedwithin the receptacle 432 of the receiver member 408. The opening 440 isslightly smaller than the diameter of the head 8 of the anchor member 7,and thus there will be a tactile and/or audible indication as to whenthe anchor member 7 is received within the receiver member 408. Oncethis indication is relayed, the user then turns the thumbwheel 412 tolock the head 8 within the receiver member 408. Clockwise rotation ofthe thumbwheel 412 causes the shaft 410 (through the threaded engagementbetween the threaded region 448 of the shaft 410 and the threaded lumen454 of the thumbwheel 412) to migrate proximally through the inserter400. Due to the engagement between the connectors 452 and the receivermember 408, a proximal migration of the shaft 410 causes a proximalmigration of the receiver member 408. This in turn draws the distal end426 of the receiver member 408 through the distal aperture 494 of theengagement assembly 406. As this happens, the raised surface 436interacts with the distal aperture 494 to cause the flanges 436 to bedeflected radially inward. This causes the concave surfaces 438 tobecome engaged with the head 8 and/or neck 9 of the anchor member 7,thereby securely locking the anchor member 7 to the inserter 400. Theassembly comprising the hoop shim assembly 6, anchor member 7, retractorblade 14, and inserter 400 is now ready for use.

To disengage the inserter 400 from the anchor member 7, the thumbwheel412 is rotated in a counterclockwise direction. This rotation reversesthe effects described above, and releases the inserter 400 from theanchor member 7. The inserter 400 may then be slidably removed from theretractor blade 14.

FIGS. 79-82 illustrate an example embodiment of a reattachment tool 500for use with the tissue retraction system 10. The reattachment tool 500may be used to simplify the act of reattaching a hoop shim 6 (andretractor blade 14, 16) to the head of an implanted bone anchor 7, inthe event the hoop shim 6 becomes inadvertently or intentionallydisengaged. For example, during the procedure the user may decide toswap out one or both of the retractor blades 14, 16 with longer orshorter blades. To do this, the user the user may disengage the hoopshim 6 from the bone anchor 7, with the hoop shim removal tool 350. Thehoop shim 6 and retractor blade 14, 16 are removed from the operativecorridor while the bone anchor 7 remains anchored. The new blade 14, 16and hoop shim 6 are engaged, as described above, with the hoop shim 6 inthe unlocked position. The reattachment tool 500 is then engaged withthe retractor blade 14, 16 above the hoop shim 6 and the blade, hoopshim, and reattachment tool are advanced towards the bone anchor 7. Thehoop member is then attached over the bone anchor 7 and the hoop shim islocked.

The reattachment tool 500 includes an outer body 502, an anchor engagingmember 504, a shim engaging member 506, and a blade engaging member 508.With reference to FIGS. 80-81, the anchor engaging member 502 includes ashaft 510 terminating in a distal head 512 with a spherical pocket 514.The anchor engaging member is spring loaded in a distal cavity 516 ofthe body 502. The shaft 510 has a neck region 518 with a diameter thatis larger than the rest of the shaft 510. A spring 520 encircling theshaft 510 is captured between the neck 516 and a back wall 522 of thecavity 516. A pin 526 traversing through cavity 516 prevents passage ofthe neck 518, keeping the anchor engagement member 504 fixed in the body502. A cutout 526 between the distal head 512 and the neck 518 permitsthe anchor engaging member to slide along the pin 524 between a neutralposition wherein the distal head 512 extends out of the body 502 and adepressed position wherein the distal head 512 is fully received withinthe body 512. With the anchor engaging member 504 contacting the head 8of bone anchor 7, downward pressure is applied to the body 502 causingthe distal head 512 of the anchor engaging member 504 to retract intothe body 502 as the body 502 advanced towards the anchor site. Theopening 528 at the distal end of the body 502 is large enough to receivethe head 8 therein. As the head 8 is received into the body 502, thedistal end presses the hoop member 304 over the head 8, such that thehoop shim 6 and bone anchor 7 are engaged in the unlocked position. Thespherical pocket 514 of the distal head 512 complements the head 8 ofthe bone anchor 7 to help maintain engagement and alignment of thedistal head 512 and anchor head 8. A handle 530 is preferably includedto facilitate use of the reattachment tool.

The shim engaging element 506 has a base 532 and an arm 534 ending in apair of fingers 536. The base 532 is spring loaded in a proximal cavity536 of the body 502. The arm 534 and fingers 536 extend along theoutside of body 502. Slot 538 in body 502 allows the base 532 and arm534 to travel along the body 532. A spring 540 is captured between afront wall 542 of the proximal cavity 536 and the base 532 and holds theshim engaging element 506 in a neutral position. Fingers 536 slidablyengage the track grooves 252 of the retractor blade 14, 16 and restabove the top of the shim element 302 of the hoop shim 6 when in theneutral position. Pusher 544 connects to the base 532 through a proximalend 548 of the body 502 and is used to advance the shim engaging element506 distally towards the hoop shim 6. After reengaging the hoop member304 over the anchor head 8, and with the distal end of the body stillpressed against the hoop member 304 at the anchor site (and thus withthe anchor head 8 still captured within the body 502), the pusher isused to apply downward force to the shim element 302, via the fingers536, to move the hoop shim into the locked configuration. The pusher 544preferably includes an enlarged end 546 for easier use.

The blade engagement member 508 extends from the body 502 and includes adeflectable flange 550 extending thereon. The deflectable flange 550includes a knob 552 configured to be received within the recesses 250 inthe retractor blade 14, 16. When the knob 552 is reattachment tool 500is being advanced along the retractor blade 14, 16, the knob 552 isforced out of the recess 250 and the flange 550 is deflected and understress. When the knob 552 enters the next recess 250, the flange 550snaps back into its initial position. This provides both a tactile andaudible indication of the sequential advancement of the knob 552 alongthe series of recesses 250, as well as a secure (but releasable)engagement to the retractor blade 14, 16. The fingers 536 of the shimengaging element are situated on either side of the blade engagingelement 508 and slidably engage the track grooves.

Turing to FIGS. 83-86, the surgical fixation system described herein maybe provided with a number of additional features or accessories. Forexample, as depicted in FIG. 83, a light cable 554 capable of couplingto the retractor blade assemblies and illuminating the operativecorridor without obstructing the surgeon's view may be provided. Thelight cable 554 has an offset distal end 556 and wing extensions 558beginning proximally to the offset distal end. In this configuration thedistal end 556 can slide over the shim element 302 when the light cableis advanced down the track grooves 252, as shown in FIG. 84. Byextending the distal end 556 over the shim element 302 of the hoop shim,glare that might occur from light reflecting off of the shim element 302is negated. An o-ring 560 disposed around the distal end 558 engages theslot 340 of the shim element 302 to secure the light cable 554 fromunwanted movement. The light cable may be bendable but also capable ofholding its bended such that the proximal portions can be bended out ofthe way after exiting the retractor blade.

By way of further example, tissue shims 562 are capable of coupling tothe retractor blade assemblies to extend the width of the retractorblades. The tissue shims 562 include a blade engaging portion 564. Theblade engaging portion includes wing extensions (not shown) thatslidably engage the track grooves 252 of the retractor blade 14, 16. Adeflectable tab 566 similar those previously described engages thenotches 250 on the interior face of the retractor blades 14, 16 tosecure the position of the tissue shim 562 along the retractor blade.Branches 568 extend outward and downward from the blade engaging portion564, such that when the blade engaging portion 564 is slidably receiveddown the track grooves 252 of the retractor blade 14, 16, the branches568 extend down to the target site, or nearly so, while the bladeengaging portion remains above the shim element 302 of the hoop shim 6.The light cable 554 may be inserted above the tissue shim 562.

Still by way of further example, though not shown, a fourth bladeattachment may be provided that independently places a fourth retractorblade within the operative corridor opposite the medial retractor blade.The fourth retractor blade assembly may be attached to retractor body,medial blade assembly, or either of the first or second (or both)retractor blade assemblies. The fourth retractor blade may be attachedto the retractor body so as to allow multi axial movement or polyaxialmovement. The fourth retractor blade may be used to expand the operativecorridor laterally to expose the transverse processes. The fourthretractor blade may be similar to the third retractor blade 18 describedabove. The blade extension of the fourth retractor blade may be freefloating as described for retractor blade 18 or it may be fixed. Ineither case, it is intended that the distal end of the forth retractorblade may elevate tissue off of the bone as it is extend or sweptlaterally. Exposing the transverse processes in this manner may providethe ability to increase fusion of the adjacent vertebrae by fusing thetransverse processes together.

According to yet still another example, a malleable wall barrier may beprovided that can be inserted between the retractor blades and thesurrounding soft tissue to help keep the soft tissue out of theoperative corridor and surgical target site. This malleable barrier maybe semi-rigid in that it can be formed to conform to a desired shape yethold this shape under pressure from the surrounding tissue. It iscontemplated that this malleable barrier be supported by the retractorblades, but not necessarily attached to them. The malleable barrier mayalso extend out of the operative corridor (out of the patient) and becapable of being “folded” to lie on the patient's skin so as to be outof the surgeon's way.

While the retractor system 10 and methods described above have beendirected towards single level fusion, it is possible to perform multiplelevel fusions using the retractor system 10. This may be accomplished ina number of different fashions. For example, the steps described abovecan be completed in the same fashion expect that the blade-shim-anchorassemblies are implanted in the pedicles of the vertebra at either endof the multi level spinal segment such that the operative corridorsimply spans the entire segment. Alternatively, the operative corridormay be adjusted to expose each level of the multi level fusionsequentially. In this case, a third blade-shim-anchor assembly isadvanced and anchored into the pedicle of the additional vertebra. Forefficiency, this step may be performed at the same time theblade-shim-anchor assemblies are anchored to the first and secondpedicles or it may be performed once the user is ready to begin work onthe additional level(s). The hoop shim 6 is disengaged from the boneanchor 7 at the middle vertebrae of the segment and the retractor blade14 or 16 is removed and replaced with a retractor blade 16 or 14,respectively, that faces the opposite direction (and the added thirdretractor blade). In one example this may be accomplished using thereattachment tool 500 as described above. According to another example,an alternate retractor blade 600 may be provided to facilitate swappingof the left and right facing blade at the middle level.

FIG. 87 illustrates an alternate retractor blade 600 that may be usedwith the retractor assembly 10 to facilitate multilevel procedures. Theretractor blade 600 is similar to blade 14, 16 described above andincludes an attachment portion 602 and a blade portion 604. Theattachment portion 602 is generally identical to the attachment portion220 of retractor blade 14, 16, such that repeat discussion isunnecessary.

The blade portion 604 is also similar to the blade portion 222 ofretractor blade 14, 16 in that it extends distally from the attachmentportion 602 and includes an outside surface 606, an inside surface 608,a first lip 610, and a second lip 611. The first lip 610 and second lip611 comprise edges of the blade portion 604 and each extend along thelength of the blade portion from the attachment portion 602 to thedistal end of the blade portion 604. The first and second lips 610, 611are asymmetric relative to one another. For example, the first lip 610has a concave portion 613 that allows for clearance of spinal anatomyduring blade angulation. The outside surface is a smooth arcuate surfaceconfigured to interact with the patient's soft tissue near the operativecorridor. The outside surface 606 extends from the attachment portion602 at a non-orthogonal angle relative to the top surface of theattachment portion. Since much of the blade has a generally uniformthickness, the inside surface 608 extends from the attachment portion602 at the same non-orthogonal angle relative to the top surface. Thus,the effect is that the operative corridor is immediately establishedhaving a conical shape with no further adjustment of the tissueretraction assembly 10 required. Additionally, the blade portion extendsfrom the attachment portion 602 such that the blade face is orientedorthogonal to the attachment portion 602. Thus, when the retractor blade600 is attached to the retractor body 10, the inside surface 608 facesthe operative corridor at an angle, for example between 20 and 60degrees). This orientation of the blade portion relative to theattachment portion helps optimize the shape of the operative corridor.

Where the retractor blade 600 differs from the retractor blade 14, 16,is in that the inside surface 608 is not formed of a single surface, butrather it includes a track insert 612. As best viewed in FIG. 88, innersurface 608 has recess 614 which slidably receives the track insert 612from the bottom of the blade portion. Edges 616 of the track insert 612slide into grooves 618 formed in the sides of the recess 614. Adeflectable tab 620 extends into the recess 614 pointing upward. As thetrack insert 612 advances into the recess 614 it deflects the tab 620allowing the insert 612 to pass. When the track insert 612 is fullyinserted into the recess 614 it abuts an upper portion 622 such that thetrack insert 612 and upper portion form a generally flush inner face.Together, the upper portion 622 and track insert 612 also define trackgrooves 630 that slidably receive the shim element 302 (as well as theinserter 400, reattachment tool 500, light cable 554, tissue shim 562,and guide 650, for example). The deflectable tab 620 aligns with ahorizontal aperture 624 near the top of the track insert 612 when thetrack insert is fully inserted and the tab 20 returns to a naturalposition, catching the horizontal aperture like a hook such that thetrack insert cannot disengage from the recess 614. The track insertincludes stops 632 that prevent the hoop shim 6 from disengaging fromthe bottom. The upper portion 622 and the track insert 612 both includenotches 626 that function like the notches 252 described above.

Initially, the hoop shim 6 and bone anchor 7 may be engaged to theretractor blade 600, coupled to the inserter 400, and implanted into theappropriate pedicle as described above for blade 14, 16. To replace theblade 600 with an opposite facing blade 600′(or to simply change bladesfor a longer or shorter blade), rather than removing the hoop shim 6 andreattaching the hoop shim together with a new blade, as described above,the hoop shim 6 and track insert 612 remain attached to the bone anchor7 (as in FIG. 91) and a new retractor blade 600′ (having the desired neworientation or size) slides onto the track insert 612.

With reference to FIGS. 92-100, a guide instrument 650 according to anexample embodiment is pictured. The Guide instrument functions to bothdisengage the track insert 612 from the deflectable tab 620 and to guidethe new blade onto the track insert 612. The guide 650 includes a driver652, an actuator 654, and a body 656. The body 656 has a generallytubular outer shaft 658 fitted with a handle 660 at the proximal end anda housing 662 at the distal end. The underside of the outer shaft 658includes an engagement plate 664 that slidably engages the track grooves630 of the blade portion 604. The housing 662 holds the actuator 655 andhas an opening 666 through the engagement plate 664. The driver 652 hasa knob 668 to facilitate rotation of the driver. The distal end 670 ofthe driver includes a projection 672. By way of example, the projectionshown has a generally half circle shape. The projection 672 is offsetfrom the center of the distal end 670 such that rotation of the driver652 causes the height of the projection 672 to change as it travels thecircumference. The projection 672 extends into housing 662 and rests inslot 674 of the actuator 654. As projection 672 travels along thecircumference of the distal end 670, it drives the actuator 654 up ordown. When the actuator is forced to the bottom of the housing 662, thatis when the actuator is in a locked position, a horizontal extension 676extends through the opening 666. When fully engaged with the retractorblade 600, the horizontal extension 676 aligns with the horizontalaperture 624 of the track insert. The horizontal extension 676 passesthrough the horizontal aperture 624, deflecting the tab 620 inward andreleasing the track insert 612 from the rest of retractor blade 600. Theblade 600 can then be removed by sliding the blade along the engagementplate 664. The guide 650 remains in place and the replacement retractorblade 600′ slides down the engagement plate 664 onto the track insert612. Rotating the driver to the unlocked position draws the horizontalextension 676 into the housing 662 and the deflectable tab 620 replacesthe horizontal extension in the horizontal aperture.

With reference now to FIGS. 101-108, the surgical retraction system 10is demonstrated in use for performing a multi level TLIF procedure. Byway of example, the multi level procedure begins the same way as thesingle level procedure described above (except that theanchor-shim-blade combination for the third vertebra may be placed atthe same time as the others) and with reference to FIGS. 47-57. Thisdescription of the multi level procedure picks up after the user hascompleted work at the first level (e.g. performed a discectomy andimplanted a fusion implant), but before the spinal rod is insertedconnecting the anchors 7 (FIG. 51). The hoop shim 6 is removed from theouter vertebra of the completed level, a bone anchor receiver isattached to anchor 7, and the corresponding retractor blade 16 isremoved. The guide instrument 650 is advanced down the track grooves ofthe middle blade (i.e. the retractor blade positioned over the centervertebra of the multi level segment) (FIG. 101). When fully seated, theguide 650 is actuated to engage the horizontal extension 676 into thehorizontal aperture 624 to disengage the tab 620. With the tab 620disengaged, the retractor blade 600 is removed leaving the track insert612 and guide 650 attached to anchor 7 via the hoop shim 6 (FIG. 102).

The new retractor blade 600′ is slidably engaged to the guide 650 andadvanced into the operative corridor along the engagement plate 664 ofthe guide. When the retractor blade recess 614 of blade 600′ has fullyreceived the track insert 612, the guide 650 is actuated to release thedeflectable tab 620, locking the track insert 612 to the new blade 600′.The guide 650 is then removed.

At this point, with the retractor blades 14, 600′ protruding from theincision and the distal ends of the blades being securely registered tothe anchor members 7 via the hoop shim assemblies 6, the retractorblades 14, 600′ may be attached to the retractor body 14 (FIG. 104). Thesurgeon may then operate the retractor body 12 to cause the retractorblades 14, 14, 600′ to move in cranial and caudal directions,respectively, at the skin level. As previously described, because thedistal portions of the retractor blades 14, 600′ are securely (andpolyaxially) registered to the implanted anchor members 7, the distalend of the blades will not move. However, the angle of the retractorblades 14, 600′ relative to the anchor members 7 may be adjusted to adesired angle and the new operative corridor will be established to thesecond spinal level. Once established, the retractor body 12 may belocked to an articulating arm (not shown) by either one of theattachment members 53 of the retractor body 12, or attachment members109 of the medial rack 108. Using a suitable tool or a finger, thesurgeon then releases soft tissue from the facet. A medial retractorblade 16 may then be inserted and retracted as desired (FIG. 105). Asmentioned previously, the medial retractor blade may operate to clearremaining soft tissue from the facet. The medial retractor blade 16 maybe angled to match the operative corridor by pivoting the blade in aplane that is transverse to the longitudinal axis of the medial rack108. In this fashion, the entire operative corridor may be establishedat an angle that is suitable for superior access to the disc space.

At this point, with the new operative corridor 4′ established, and hasdistinct landmarks (i.e. the implanted anchor members 7) delineating thecranial and caudal boundaries of the new operative window. The surgeoncan now perform the necessary steps to clean out the intervertebral discspace and perform the interbody fusion procedure. As above, this mayinclude a facetectomy in which at least a portion of the facet joint isremoved, allowing access to the intervertebral disc space and adiscectomy. The interbody implant is then inserted into the cleaned outdisc space. By way of example only this may include, but not be limitedto, inserting one or more artificial or allograft implants within theintervertebral space. According to one example, the implant may beinserted and positioned obliquely across the disc space. If necessary,the surgeon may use the tissue retraction system 10 to distract the discspace with the retractor body 12.

After placement of the interbody implant, the distraction off the screwsis released, and the hoop shim assemblies 6 are removed using the hoopshim removal tool 350 as described above. The surgeon then “opens” theretractor slightly in a caudal-cranial direction using the thumbscrews240 on the blades (opposed to the rack assembly 22) as described belowto increase the space around the pedicle screws. The pedicle screwreceivers or tulips are then inserted onto the pedicle screw and theretractor blade 600′ can be actuated to expand out to the first anchorof the first vertebra (preferably by splaying the distal portion of theretractor blade to minimize expansion at the top of the operativecorridor. A spinal fixation rod is then placed within the tulips,followed by compression (if necessary). With the procedure is completed,the retractor can be returned to a “closed” position and then removedfrom the patient, closing the operative corridor. The surgeon will thenclose the operative wound, completing the procedure.

Although described with respect to specific examples of the differentembodiments, any features of the systems and methods disclosed herein byway of example only may be applied to any of the embodiments withoutdeparting from the scope of the present invention. Furthermore,procedures described for example only involving specific structure (e.g.vertebral bone) may be applied to another structure (e.g. femur) withoutdeparting from the scope of the present invention. While this inventionhas been described in terms of a best mode for achieving thisinvention's objectives, it will be appreciated by those skilled in theart that variations may be accomplished in view of these teachingswithout deviating from the spirit or scope of the invention.

One advantageous feature of the surgical fixation and retraction systemdescribed herein is the registration of the distal ends of the retractorblades 14, 16 to the implanted bone anchors 7. Although described hereinby way example as using a hoop shim assembly 6 to accomplish thispurpose, other attachment mechanisms are possible, including but notlimited to sutures, cables, hooks, etc.

The example method of performing surgery described herein disclosed theuse of an electrified tap, in order to enable pedicle integrity testingduring pilot hole formation. However, the system described herein may beprovided with additional features to enable pedicle integrity testingbefore, during, and after placement of the bone anchors within thepedicle. For example, using the electrified tap as described above isone way to test for pedicle integrity prior to placement of the boneanchors. However, the system may be equipped to continuously monitor forpedicle integrity during placement of the bone anchors as well. Forexample, the blade-anchor-shim-inserter assembly may be substantiallyinsulated, either through an insulative coating or an external barrier(e.g. sheath, cannula, etc) such that only a portion of the bone anchor(e.g. the distal tip) is electrified to deliver stimulation to evoke anEMG response. EMG monitoring can be continuous to test for potentialpedicle breach during placement of the bone anchors. Moreover, pedicleintegrity can be further tested for upon final placement of the boneanchors.

Although shown and described herein in use with a specific example of aTLIF procedure on a human spine, the tissue retraction assembly hereinmay be used for a variety of different procedures involving any parts ofthe body. The surgical fixation system described herein is well suitedfor use in any procedure involving decompression using bone anchors. Thesurgical fixation system can be used for any type of bony fusion,including discectomy and fusion. Within the spine space apart fromfusion, the tissue retraction system can be used to create an operativecorridor to enable any type of procedure, including but not limited tovertebral augmentation and vertebroplasty.

By way of example only, the various components of the surgical fixationsystem described herein may be manufactured of any material suitable toachieve the goals of stability and rigidity, including the ability touse the blades to distract the bony segments. By way of example only,the retractor body and retractor blades are made of stainless steel,however any metallic substance is possible without departing from thescope of the present invention. Moreover, any part of the systemdescribed herein, including for example the retractor blades, may becomposed of image-friendly material such as carbon fiber reinforcedpolymer (CFRP) or poly-ether-ether-ketone (PEEK) without departing fromthe scope of the present invention. The ability to intraoperativelyswitch out retractor blades may be advantageous in that one or moreimage-friendly retractor blades may be used to initially establish theworking channel, and then be intraoperatively exchanged for a stainlesssteel retractor blade in the event that the surgeon wishes to use theblades to distract the disc space.

What is claimed is:
 1. A retractor for creating an operative corridor toa surgical target, the retractor comprising: a retractor body whichincludes a first arm and a second arm, the first arm and the second armbeing movable relative to each other in a first direction; a firstretractor blade attachable to first arm, the first retractor bladeincluding a first hoop extending orthogonally from the distal end of thefirst blade, configured to releasably couple to a partially sphericalbone anchor head, and a first locking mechanism configured to cause thefirst hoop to assume an unlocked position which allows passage of thebone anchor head and a locked position which prevents passage of thebone anchor head; and a second retractor blade attachable to the secondarm, the second retractor blade including a second hoop extendingorthogonally from the distal end of the second blade, configured toreleasably couple to a partially spherical bone anchor head, and asecond locking mechanism configured to cause the second hoop to assumean unlocked position which allows passage of the bone anchor head and alocked position which prevents passage of the bone anchor head.
 2. Theretractor of claim 1, comprising a third arm movable relative to thefirst arm and the second arm in a second direction orthogonal to thefirst direction; and a third retractor blade attachable to the thirdarm.
 3. The retractor of claim 2, wherein the third retractor blade ispivotable relative to the third arm.
 4. The retractor of claim 3,wherein the third retractor blade is pivotable relative to the third armin the first direction.
 5. The retractor of claim 2, wherein the thirdblade comprises a distal anchor element.
 6. The retractor of claim 5,wherein the distal anchor element is selected from the group consistingof: a series of ridges, a series of spike members, and a combination ofthe foregoing.
 7. The retractor of claim 1, wherein at least one of thefirst and second retractor blades is capable of multiaxial movementrelative to the retractor body.
 8. The retractor of claim 7, wherein thefirst and second retractor blades are capable of multiaxial movementrelative to the retractor body.
 9. The retractor of claim 7, wherein atleast one of the first and second retractor blades is configured topivot in both a caudal and cranial direction.
 10. The retractor of claim9, wherein the first and second retractor blade are configured to pivotin both a caudal and cranial direction.
 11. The retractor of claim 1,wherein at least one of the first and second retractor blades is capableof polyaxial movement relative to the retractor body.
 12. The retractorof claim 11, wherein at least one of the first and second retractorblades is capable of polyaxial movement relative to the retractor body.13. The retractor of claim 1, wherein the first retractor blade isattached to the first arm, and the second retractor blade is attached tothe second arm.
 14. The retractor of claim 1, comprising a first boneanchor connected to the first hoop and a second bone anchor connected tothe second hoop.
 15. The retractor of claim 1, wherein said retractor isconfigured to advance to the surgical target site sequentially orsimultaneously.
 16. The retractor of claim 1, wherein the body comprisesa rack connected to the first and second arms and configured to slidethe first arm and the second arm relative to one another in the firstdirection.
 17. The retractor of claim 16, wherein said rack includes: afirst elongated axial rack member having a first plurality of teethslidably engaged to the body; and a second elongated axial rack memberhaving a second plurality of teeth slidably engaged to the body.
 18. Theretractor of claim 17, wherein the first elongated axial rack member isconnected to the first arm.
 19. The retractor of claim 17, wherein thesecond elongated axial rack member is connected to the second arm. 20.The retractor of claim 1, wherein the body comprises a first toggle tolock and unlock the ability of the first arm and the second arm to movein the first direction relative to one another.
 21. The retractor ofclaim 1, wherein: the first hoop in the unlocked position has anunlocked width allowing passage of the bone anchor head; the first hoopin the locked position has a locked width disallowing passage of thebone anchor head; the second hoop in the unlocked position has anunlocked width allowing passage of the bone anchor head; and the secondhoop in the locked position has a locked width disallowing passage ofthe bone anchor head.